diff --git a/apps/client/src/network/handlers/GameHandler.ts b/apps/client/src/network/handlers/GameHandler.ts
index 979e679..7783fc6 100644
--- a/apps/client/src/network/handlers/GameHandler.ts
+++ b/apps/client/src/network/handlers/GameHandler.ts
@@ -6,6 +6,7 @@
 import type { Socket } from "socket.io-client";
 import { protocol } from "@repo/shared";
 import type {
+  BombPlacedAckPayload,
   BombPlacedPayload,
   CurrentPlayersPayload,
   GameResultPayload,
@@ -40,6 +41,8 @@
   offGameResult: (callback: (payload: GameResultPayload) => void) => void;
   onBombPlaced: (callback: (payload: BombPlacedPayload) => void) => void;
   offBombPlaced: (callback: (payload: BombPlacedPayload) => void) => void;
+  onBombPlacedAck: (callback: (payload: BombPlacedAckPayload) => void) => void;
+  offBombPlacedAck: (callback: (payload: BombPlacedAckPayload) => void) => void;
   sendMove: (x: number, y: number) => void;
   sendPlaceBomb: (payload: PlaceBombPayload) => void;
   readyForGame: () => void;
@@ -107,6 +110,12 @@
     offBombPlaced: (callback) => {
       offEvent(protocol.SocketEvents.BOMB_PLACED, callback);
     },
+    onBombPlacedAck: (callback) => {
+      onEvent(protocol.SocketEvents.BOMB_PLACED_ACK, callback);
+    },
+    offBombPlacedAck: (callback) => {
+      offEvent(protocol.SocketEvents.BOMB_PLACED_ACK, callback);
+    },
     sendMove: (x, y) => {
       const payload: MovePayload = { x, y };
       emitEvent(protocol.SocketEvents.MOVE, payload);
diff --git a/apps/client/src/scenes/game/GameManager.ts b/apps/client/src/scenes/game/GameManager.ts
index c3c61d7..99066d8 100644
--- a/apps/client/src/scenes/game/GameManager.ts
+++ b/apps/client/src/scenes/game/GameManager.ts
@@ -4,7 +4,7 @@
  * マップ，ネットワーク同期，ゲームループを統合する
  */
 import { Application, Container, Ticker } from "pixi.js";
-import type { BombPlacedPayload } from "@repo/shared";
+import type { BombPlacedAckPayload, BombPlacedPayload } from "@repo/shared";
 import { socketManager } from "@client/network/SocketManager";
 import { GameMapController } from "./entities/map/GameMapController";
 import { BombManager } from "./entities/bomb/BombManager";
@@ -46,8 +46,12 @@
     return placed.tempBombId;
   }
 
-  public applyPlacedBomb(payload: BombPlacedPayload): void {
-    this.bombManager?.applyPlacedBomb(payload);
+  public applyPlacedBombFromOthers(payload: BombPlacedPayload): void {
+    this.bombManager?.applyPlacedBombFromOthers(payload);
+  }
+
+  public applyPlacedBombAck(payload: BombPlacedAckPayload): void {
+    this.bombManager?.applyPlacedBombAck(payload);
   }
   
   // 入力と状態管理
@@ -96,8 +100,11 @@
       gameMap: this.gameMap,
       onGameStart: this.setGameStart.bind(this),
       onGameEnd: this.lockInput.bind(this),
-      onBombPlacedFromNetwork: (payload) => {
-        this.applyPlacedBomb(payload);
+      onBombPlacedFromOthers: (payload) => {
+        this.applyPlacedBombFromOthers(payload);
+      },
+      onBombPlacedAckFromNetwork: (payload) => {
+        this.applyPlacedBombAck(payload);
       },
     });
     this.networkSync.bind();
diff --git a/apps/client/src/scenes/game/application/GameNetworkSync.ts b/apps/client/src/scenes/game/application/GameNetworkSync.ts
index eed8e01..c4bebb1 100644
--- a/apps/client/src/scenes/game/application/GameNetworkSync.ts
+++ b/apps/client/src/scenes/game/application/GameNetworkSync.ts
@@ -5,6 +5,7 @@
  */
 import { Container } from "pixi.js";
 import type {
+  BombPlacedAckPayload,
   BombPlacedPayload,
   CurrentPlayersPayload,
   GameStartPayload,
@@ -27,7 +28,8 @@
   gameMap: GameMapController;
   onGameStart: (startTime: number) => void;
   onGameEnd: () => void;
-  onBombPlacedFromNetwork: (payload: BombPlacedPayload) => void;
+  onBombPlacedFromOthers: (payload: BombPlacedPayload) => void;
+  onBombPlacedAckFromNetwork: (payload: BombPlacedAckPayload) => void;
 };
 
 /** ゲーム中のネットワークイベント購読と同期処理を管理する */
@@ -38,7 +40,8 @@
   private gameMap: GameMapController;
   private onGameStart: (startTime: number) => void;
   private onGameEnd: () => void;
-  private onBombPlacedFromNetwork: (payload: BombPlacedPayload) => void;
+  private onBombPlacedFromOthers: (payload: BombPlacedPayload) => void;
+  private onBombPlacedAckFromNetwork: (payload: BombPlacedAckPayload) => void;
   private isBound = false;
 
   private debugLog = (message: string) => {
@@ -98,7 +101,11 @@
   };
 
   private handleBombPlaced = (payload: BombPlacedPayload) => {
-    this.onBombPlacedFromNetwork(payload);
+    this.onBombPlacedFromOthers(payload);
+  };
+
+  private handleBombPlacedAck = (payload: BombPlacedAckPayload) => {
+    this.onBombPlacedAckFromNetwork(payload);
   };
 
   constructor({
@@ -108,7 +115,8 @@
     gameMap,
     onGameStart,
     onGameEnd,
-    onBombPlacedFromNetwork,
+    onBombPlacedFromOthers,
+    onBombPlacedAckFromNetwork,
   }: GameNetworkSyncOptions) {
     this.worldContainer = worldContainer;
     this.players = players;
@@ -116,7 +124,8 @@
     this.gameMap = gameMap;
     this.onGameStart = onGameStart;
     this.onGameEnd = onGameEnd;
-    this.onBombPlacedFromNetwork = onBombPlacedFromNetwork;
+    this.onBombPlacedFromOthers = onBombPlacedFromOthers;
+    this.onBombPlacedAckFromNetwork = onBombPlacedAckFromNetwork;
   }
 
   public bind() {
@@ -130,6 +139,7 @@
     socketManager.game.onUpdateMapCells(this.handleUpdateMapCells);
     socketManager.game.onGameEnd(this.handleGameEnd);
     socketManager.game.onBombPlaced(this.handleBombPlaced);
+    socketManager.game.onBombPlacedAck(this.handleBombPlacedAck);
 
     this.isBound = true;
   }
@@ -145,6 +155,7 @@
     socketManager.game.offUpdateMapCells(this.handleUpdateMapCells);
     socketManager.game.offGameEnd(this.handleGameEnd);
     socketManager.game.offBombPlaced(this.handleBombPlaced);
+    socketManager.game.offBombPlacedAck(this.handleBombPlacedAck);
 
     this.isBound = false;
   }
diff --git a/apps/client/src/scenes/game/entities/bomb/BombManager.ts b/apps/client/src/scenes/game/entities/bomb/BombManager.ts
index 00f4d28..de4f0f5 100644
--- a/apps/client/src/scenes/game/entities/bomb/BombManager.ts
+++ b/apps/client/src/scenes/game/entities/bomb/BombManager.ts
@@ -5,7 +5,11 @@
  */
 import type { Container } from "pixi.js";
 import { config } from "@client/config";
-import type { BombPlacedPayload, PlaceBombPayload } from "@repo/shared";
+import type {
+  BombPlacedAckPayload,
+  BombPlacedPayload,
+  PlaceBombPayload,
+} from "@repo/shared";
 import { LocalPlayerController } from "@client/scenes/game/entities/player/PlayerController";
 import { BombController } from "./BombController";
 import type { GamePlayers } from "@client/scenes/game/application/game.types";
@@ -85,19 +89,26 @@
     };
   }
 
-  /** サーバー確定イベントを反映し，必要なら仮IDから正式IDへ置換する */
-  public applyPlacedBomb(payload: BombPlacedPayload): void {
-    if (payload.ownerId === this.myId) {
-      const tempBombId = this.pendingOwnRequestToTempBombId.get(payload.requestId);
-      if (tempBombId) {
-        this.removePendingRequestByRequestId(payload.requestId);
-        if (tempBombId !== payload.bombId) {
-          this.removeBomb(tempBombId);
-        }
-      }
+  /** 他プレイヤー向けの爆弾確定イベントを反映する */
+  public applyPlacedBombFromOthers(payload: BombPlacedPayload): void {
+    this.upsertBomb(payload.bombId, this.toRenderPayload(payload));
+  }
+
+  /** 設置者本人向けACKを反映し，仮IDから正式IDへ置換する */
+  public applyPlacedBombAck(payload: BombPlacedAckPayload): void {
+    const tempBombId = this.pendingOwnRequestToTempBombId.get(payload.requestId);
+    if (!tempBombId) {
+      return;
     }
 
-    this.upsertBomb(payload.bombId, this.toRenderPayload(payload));
+    const tempPayload = this.bombRenderPayloadById.get(tempBombId);
+    this.removePendingRequestByRequestId(payload.requestId);
+    if (!tempPayload || tempBombId === payload.bombId) {
+      return;
+    }
+
+    this.removeBomb(tempBombId);
+    this.upsertBomb(payload.bombId, tempPayload);
   }
 
   /** 描画ペイロードで指定IDの爆弾を追加または更新する */
@@ -170,9 +181,9 @@
     };
   }
 
-  private createRequestId(elapsedMs: number): string {
+  private createRequestId(_elapsedMs: number): string {
     this.requestSerial += 1;
-    return `${this.myId}:${elapsedMs}:${this.requestSerial}`;
+    return `${this.requestSerial}`;
   }
 
   private createTempBombId(requestId: string): string {
diff --git a/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts b/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
index 02578b3..53bfee3 100644
--- a/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
+++ b/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
@@ -3,6 +3,7 @@
  * ゲーム系ユースケースが利用する入力ポートと出力ポートの契約を定義する
  */
 import type {
+  BombPlacedAckPayload,
   BombPlacedPayload,
   gameTypes,
   playerTypes,
@@ -69,7 +70,12 @@
 
 /** 爆弾ユースケースが利用する送信出力ポート */
 export interface BombOutputPort {
-  publishBombPlacedToRoom(roomId: roomTypes.Room["roomId"], payload: BombPlacedPayload): void;
+  publishBombPlacedToOthersInRoom(
+    roomId: roomTypes.Room["roomId"],
+    ownerSocketId: string,
+    payload: BombPlacedPayload
+  ): void;
+  publishBombPlacedAckToSocket(socketId: string, payload: BombPlacedAckPayload): void;
 }
 
 /** 爆弾設置ユースケースが利用する爆弾状態入力ポート */
diff --git a/apps/server/src/domains/game/application/services/GameRoomSession.ts b/apps/server/src/domains/game/application/services/GameRoomSession.ts
index 54a5abf..5759e6f 100644
--- a/apps/server/src/domains/game/application/services/GameRoomSession.ts
+++ b/apps/server/src/domains/game/application/services/GameRoomSession.ts
@@ -122,7 +122,7 @@
   }
 
   public issueServerBombId(): string {
-    return this.bombStateStore.issueServerBombId(this.roomId);
+    return this.bombStateStore.issueServerBombId();
   }
 
   public dispose(): void {
diff --git a/apps/server/src/domains/game/application/useCases/placeBombUseCase.ts b/apps/server/src/domains/game/application/useCases/placeBombUseCase.ts
index adbf947..f3fde0e 100644
--- a/apps/server/src/domains/game/application/useCases/placeBombUseCase.ts
+++ b/apps/server/src/domains/game/application/useCases/placeBombUseCase.ts
@@ -8,6 +8,7 @@
   PlaceBombInput,
 } from "../ports/gameUseCasePorts";
 import {
+  createBombPlacedAckPayload,
   createBombDedupeKey,
   createBombPlacedPayload,
 } from "@server/domains/game/entities/bomb/bombPlacement";
@@ -38,12 +39,22 @@
     return;
   }
 
-  output.publishBombPlacedToRoom(
+  const bombId = bombStore.issueServerBombId(roomId);
+
+  output.publishBombPlacedToOthersInRoom(
     roomId,
+    input.socketId,
     createBombPlacedPayload({
       payload: input.payload,
-      bombId: bombStore.issueServerBombId(roomId),
-      ownerId: input.socketId,
+      bombId,
+    })
+  );
+
+  output.publishBombPlacedAckToSocket(
+    input.socketId,
+    createBombPlacedAckPayload({
+      requestId: input.payload.requestId,
+      bombId,
     })
   );
 };
diff --git a/apps/server/src/domains/game/application/useCases/startGameUseCase.ts b/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
index 7ec726b..d4eb749 100644
--- a/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
+++ b/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
@@ -6,6 +6,13 @@
 import { logEvent } from "@server/logging/logger";
 import { gameUseCaseLogEvents, logResults, logScopes } from "@server/logging/index";
 
+const excludeRecipientFromPlayerUpdates = <TPlayerUpdate extends { id: string }>(
+  playerUpdates: TPlayerUpdate[],
+  recipientId: string
+): TPlayerUpdate[] => {
+  return playerUpdates.filter((playerUpdate) => playerUpdate.id !== recipientId);
+};
+
 type StartGameUseCaseParams = {
   roomId: string;
   playerIds: string[];
@@ -36,8 +43,9 @@
     (tickData) => {
       if (tickData.playerUpdates.length > 0) {
         playerIds.forEach((playerId) => {
-          const updatesForPlayer = tickData.playerUpdates.filter(
-            (playerUpdate) => playerUpdate.id !== playerId
+          const updatesForPlayer = excludeRecipientFromPlayerUpdates(
+            tickData.playerUpdates,
+            playerId
           );
 
           if (updatesForPlayer.length === 0) {
diff --git a/apps/server/src/domains/game/entities/bomb/BombStateStore.ts b/apps/server/src/domains/game/entities/bomb/BombStateStore.ts
index 28a0719..92a2ea4 100644
--- a/apps/server/src/domains/game/entities/bomb/BombStateStore.ts
+++ b/apps/server/src/domains/game/entities/bomb/BombStateStore.ts
@@ -20,10 +20,8 @@
   }
 
   /** セッション単位の連番からサーバー採番の爆弾IDを生成する */
-  public issueServerBombId(roomId: string): string {
-    // roomId はセッションを外部参照するためのID名前空間として利用する
+  public issueServerBombId(): string {
     const { bombId, nextSerial } = issueServerBombId({
-      roomId,
       currentSerial: this.bombSerial,
     });
     this.bombSerial = nextSerial;
diff --git a/apps/server/src/domains/game/entities/bomb/bombIdentity.ts b/apps/server/src/domains/game/entities/bomb/bombIdentity.ts
index eaa9ba2..3eb5a31 100644
--- a/apps/server/src/domains/game/entities/bomb/bombIdentity.ts
+++ b/apps/server/src/domains/game/entities/bomb/bombIdentity.ts
@@ -4,19 +4,16 @@
  */
 
 type IssueServerBombIdParams = {
-  // セッションに紐づく外部公開用のID名前空間
-  roomId: string;
   currentSerial: number;
 };
 
 /** 次のサーバー採番爆弾IDと更新後シリアルを返す */
 export const issueServerBombId = ({
-  roomId,
   currentSerial,
 }: IssueServerBombIdParams): { bombId: string; nextSerial: number } => {
   const nextSerial = currentSerial + 1;
   return {
-    bombId: `${roomId}:${nextSerial}`,
+    bombId: `${nextSerial}`,
     nextSerial,
   };
 };
diff --git a/apps/server/src/domains/game/entities/bomb/bombPlacement.ts b/apps/server/src/domains/game/entities/bomb/bombPlacement.ts
index 98492a0..991944a 100644
--- a/apps/server/src/domains/game/entities/bomb/bombPlacement.ts
+++ b/apps/server/src/domains/game/entities/bomb/bombPlacement.ts
@@ -2,7 +2,7 @@
  * bombPlacement
  * 爆弾設置時の識別キー生成と確定ペイロード組み立てを提供する
  */
-import type { BombPlacedPayload, PlaceBombPayload } from "@repo/shared";
+import type { BombPlacedAckPayload, BombPlacedPayload, PlaceBombPayload } from "@repo/shared";
 
 /** 重複排除に利用する爆弾設置要求キーを生成する */
 export const createBombDedupeKey = (ownerId: string, requestId: string): string => {
@@ -12,18 +12,33 @@
 type CreateBombPlacedPayloadParams = {
   payload: PlaceBombPayload;
   bombId: string;
-  ownerId: string;
 };
 
-/** 爆弾確定通知で配信するペイロードを生成する */
+/** 爆弾確定通知で他プレイヤーへ配信するペイロードを生成する */
 export const createBombPlacedPayload = ({
   payload,
   bombId,
-  ownerId,
 }: CreateBombPlacedPayloadParams): BombPlacedPayload => {
   return {
-    ...payload,
     bombId,
-    ownerId,
+    x: payload.x,
+    y: payload.y,
+    explodeAtElapsedMs: payload.explodeAtElapsedMs,
+  };
+};
+
+type CreateBombPlacedAckPayloadParams = {
+  requestId: string;
+  bombId: string;
+};
+
+/** 爆弾確定通知で設置者本人へ配信するACKペイロードを生成する */
+export const createBombPlacedAckPayload = ({
+  requestId,
+  bombId,
+}: CreateBombPlacedAckPayloadParams): BombPlacedAckPayload => {
+  return {
+    requestId,
+    bombId,
   };
 };
diff --git a/apps/server/src/network/adapters/socketEmitters.ts b/apps/server/src/network/adapters/socketEmitters.ts
index 9ced072..dfe1fc3 100644
--- a/apps/server/src/network/adapters/socketEmitters.ts
+++ b/apps/server/src/network/adapters/socketEmitters.ts
@@ -15,6 +15,11 @@
   <TEvent extends SocketEventName>(roomId: string, event: TEvent, payload: ServerToClientPayloadOf<TEvent>): void;
 };
 
+type EmitToRoomExceptSocket = {
+  <TEvent extends SocketEventName>(roomId: string, excludedSocketId: string, event: TEvent): void;
+  <TEvent extends SocketEventName>(roomId: string, excludedSocketId: string, event: TEvent, payload: ServerToClientPayloadOf<TEvent>): void;
+};
+
 type EmitToSocket = {
   <TEvent extends SocketEventName>(event: TEvent): void;
   <TEvent extends SocketEventName>(event: TEvent, payload: ServerToClientPayloadOf<TEvent>): void;
@@ -51,6 +56,17 @@
   };
 };
 
+/** ルーム送信時に特定ソケットを除外する送信関数を生成する */
+export const createEmitToRoomExceptSocket = (io: Server): EmitToRoomExceptSocket => {
+  return (roomId: string, excludedSocketId: string, event: SocketEventName, payload?: unknown) => {
+    emitWithOptionalPayload(
+      (eventName, body) => io.to(roomId).except(excludedSocketId).emit(eventName, body),
+      event,
+      payload
+    );
+  };
+};
+
 /** 単一ソケット向けの送信関数を生成する */
 export const createEmitToSocket = (socket: Socket): EmitToSocket => {
   return (event: SocketEventName, payload?: unknown) => {
diff --git a/apps/server/src/network/handlers/CommonHandler.ts b/apps/server/src/network/handlers/CommonHandler.ts
index 5e728b4..6348c9d 100644
--- a/apps/server/src/network/handlers/CommonHandler.ts
+++ b/apps/server/src/network/handlers/CommonHandler.ts
@@ -6,6 +6,7 @@
 import {
   createEmitToAll,
   createEmitToRoom,
+  createEmitToRoomExceptSocket,
   createEmitToSocket,
   createEmitToSocketById,
 } from "@server/network/adapters/socketEmitters";
@@ -14,6 +15,7 @@
 export type CommonHandlerContext = {
   emitToAll: ReturnType<typeof createEmitToAll>;
   emitToRoom: ReturnType<typeof createEmitToRoom>;
+  emitToRoomExceptSocket: ReturnType<typeof createEmitToRoomExceptSocket>;
   emitToSocket: ReturnType<typeof createEmitToSocket>;
   emitToSocketById: ReturnType<typeof createEmitToSocketById>;
 };
@@ -26,6 +28,7 @@
   return {
     emitToAll: createEmitToAll(io),
     emitToRoom: createEmitToRoom(io),
+    emitToRoomExceptSocket: createEmitToRoomExceptSocket(io),
     emitToSocket: createEmitToSocket(socket),
     emitToSocketById: createEmitToSocketById(io),
   };
diff --git a/apps/server/src/network/handlers/game/createGameOutputAdapter.ts b/apps/server/src/network/handlers/game/createGameOutputAdapter.ts
index 728f8c1..4b18fd0 100644
--- a/apps/server/src/network/handlers/game/createGameOutputAdapter.ts
+++ b/apps/server/src/network/handlers/game/createGameOutputAdapter.ts
@@ -5,6 +5,7 @@
 import { Server } from "socket.io";
 import { protocol } from "@repo/shared";
 import type {
+  BombPlacedAckPayload,
   BombPlacedPayload,
   GameStartPayload,
   GameResultPayload,
@@ -60,8 +61,11 @@
     publishGameStartToSocket: (payload: GameStartPayload) => {
       common.emitToSocket(protocol.SocketEvents.GAME_START, payload);
     },
-    publishBombPlacedToRoom: (roomId: RoomId, payload: BombPlacedPayload) => {
-      common.emitToRoom(roomId, protocol.SocketEvents.BOMB_PLACED, payload);
+    publishBombPlacedToOthersInRoom: (roomId: RoomId, ownerSocketId: string, payload: BombPlacedPayload) => {
+      common.emitToRoomExceptSocket(roomId, ownerSocketId, protocol.SocketEvents.BOMB_PLACED, payload);
+    },
+    publishBombPlacedAckToSocket: (socketId: string, payload: BombPlacedAckPayload) => {
+      common.emitToSocketById(socketId, protocol.SocketEvents.BOMB_PLACED_ACK, payload);
     },
   };
 };
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index 95c5a0c..49f47b1 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -31,6 +31,7 @@
 	ServerToClientPayloadOf,
 	CurrentPlayersPayload,
 	BombPlacedPayload,
+	BombPlacedAckPayload,
 	PlaceBombPayload,
 	BombNetworkPayload,
 	GameStartPayload,
diff --git a/packages/shared/src/protocol/eventPayloads.ts b/packages/shared/src/protocol/eventPayloads.ts
index 7d7c6f6..cf0976f 100644
--- a/packages/shared/src/protocol/eventPayloads.ts
+++ b/packages/shared/src/protocol/eventPayloads.ts
@@ -25,6 +25,7 @@
   MovePayload,
   PlaceBombPayload,
   BombPlacedPayload,
+  BombPlacedAckPayload,
   GameResultPayload,
   GameResultRanking,
 } from "./payloads/gamePayloads";
diff --git a/packages/shared/src/protocol/events.ts b/packages/shared/src/protocol/events.ts
index 20329b7..cfef91b 100644
--- a/packages/shared/src/protocol/events.ts
+++ b/packages/shared/src/protocol/events.ts
@@ -24,6 +24,7 @@
   MovePayload,
   PlaceBombPayload,
   BombPlacedPayload,
+  BombPlacedAckPayload,
   PingPayload,
   PongPayload,
   JoinRoomPayload,
diff --git a/packages/shared/src/protocol/maps/gameEventPayloadMap.ts b/packages/shared/src/protocol/maps/gameEventPayloadMap.ts
index 2e79291..83b80ea 100644
--- a/packages/shared/src/protocol/maps/gameEventPayloadMap.ts
+++ b/packages/shared/src/protocol/maps/gameEventPayloadMap.ts
@@ -5,6 +5,7 @@
  */
 import { SocketEvents } from "../socketEvents";
 import type {
+  BombPlacedAckPayload,
   BombPlacedPayload,
   CurrentPlayersPayload,
   GameResultPayload,
@@ -37,6 +38,7 @@
   [SocketEvents.REMOVE_PLAYER]: RemovePlayerPayload;
   [SocketEvents.UPDATE_MAP_CELLS]: UpdateMapCellsPayload;
   [SocketEvents.BOMB_PLACED]: BombPlacedPayload;
+  [SocketEvents.BOMB_PLACED_ACK]: BombPlacedAckPayload;
   [SocketEvents.PONG]: PongPayload;
   [SocketEvents.GAME_END]: undefined;
   [SocketEvents.GAME_RESULT]: GameResultPayload;
diff --git a/packages/shared/src/protocol/payloads/gamePayloads.ts b/packages/shared/src/protocol/payloads/gamePayloads.ts
index 7353bd3..f28a522 100644
--- a/packages/shared/src/protocol/payloads/gamePayloads.ts
+++ b/packages/shared/src/protocol/payloads/gamePayloads.ts
@@ -48,8 +48,16 @@
   explodeAtElapsedMs: number;
 };
 
-/** BOMB_PLACED イベントで送受信する爆弾確定情報 */
-export type BombPlacedPayload = PlaceBombPayload & {
+/** BOMB_PLACED イベントで送受信する他プレイヤー向け爆弾確定情報 */
+export type BombPlacedPayload = {
   bombId: string;
-  ownerId: string;
+  x: number;
+  y: number;
+  explodeAtElapsedMs: number;
+};
+
+/** BOMB_PLACED_ACK イベントで送受信する設置者向け確定情報 */
+export type BombPlacedAckPayload = {
+  bombId: string;
+  requestId: string;
 };
diff --git a/packages/shared/src/protocol/socketEvents.ts b/packages/shared/src/protocol/socketEvents.ts
index 2517acf..d93cb2f 100644
--- a/packages/shared/src/protocol/socketEvents.ts
+++ b/packages/shared/src/protocol/socketEvents.ts
@@ -27,6 +27,7 @@
   PLACE_BOMB: "place-bomb",
   UPDATE_MAP_CELLS: "update_map_cells",
   BOMB_PLACED: "bomb-placed",
+  BOMB_PLACED_ACK: "bomb-placed-ack",
 
   // 時間同期・ゲーム進行関連
   PING: "ping",