diff --git a/apps/client/src/network/handlers/GameHandler.ts b/apps/client/src/network/handlers/GameHandler.ts
index fc91ec8..8005556 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 {
+  BombPlacedPayload,
   CurrentPlayersPayload,
   GameResultPayload,
   GameStartPayload,
@@ -36,7 +37,10 @@
   offGameEnd: (callback: () => void) => void;
   onGameResult: (callback: (payload: GameResultPayload) => void) => void;
   offGameResult: (callback: (payload: GameResultPayload) => void) => void;
+  onBombPlaced: (callback: (payload: BombPlacedPayload) => void) => void;
+  offBombPlaced: (callback: (payload: BombPlacedPayload) => void) => void;
   sendMove: (x: number, y: number) => void;
+  sendPlaceBomb: (payload: BombPlacedPayload) => void;
   readyForGame: () => void;
 };
 
@@ -96,10 +100,19 @@
     offGameResult: (callback) => {
       offEvent(protocol.SocketEvents.GAME_RESULT, callback);
     },
+    onBombPlaced: (callback) => {
+      onEvent(protocol.SocketEvents.BOMB_PLACED, callback);
+    },
+    offBombPlaced: (callback) => {
+      offEvent(protocol.SocketEvents.BOMB_PLACED, callback);
+    },
     sendMove: (x, y) => {
       const payload: MovePayload = { x, y };
       emitEvent(protocol.SocketEvents.MOVE, payload);
     },
+    sendPlaceBomb: (payload) => {
+      emitEvent(protocol.SocketEvents.PLACE_BOMB, payload);
+    },
     readyForGame: () => {
       emitEvent(protocol.SocketEvents.READY_FOR_GAME);
     }
diff --git a/apps/client/src/scenes/game/GameManager.ts b/apps/client/src/scenes/game/GameManager.ts
index 6bc8869..eb1f5a5 100644
--- a/apps/client/src/scenes/game/GameManager.ts
+++ b/apps/client/src/scenes/game/GameManager.ts
@@ -10,6 +10,7 @@
 import { GameNetworkSync } from "./application/GameNetworkSync";
 import { GameLoop } from "./application/GameLoop";
 import { BombManager } from "./application/BombManager";
+import { createBombIdFromPayload } from "./application/BombManager";
 import type { BombUpsertPayload } from "./application/BombManager";
 import type { GamePlayers } from "./application/game.types";
 
@@ -39,7 +40,11 @@
   public placeBomb(): string | null {
     if (this.isInputLocked) return null;
     if (!this.bombManager) return null;
-    return this.bombManager.placeBomb();
+    const placed = this.bombManager.placeBomb();
+    if (!placed) return null;
+
+    socketManager.game.sendPlaceBomb(placed.payload);
+    return placed.bombId;
   }
 
   public upsertBomb(bombId: string, payload: BombUpsertPayload): void {
@@ -96,6 +101,10 @@
       gameMap: this.gameMap,
       onGameStart: this.setGameStart.bind(this),
       onGameEnd: this.lockInput.bind(this),
+      onBombPlaced: (payload) => {
+        const bombId = createBombIdFromPayload(payload);
+        this.upsertBomb(bombId, payload);
+      },
     });
     this.networkSync.bind();
 
diff --git a/apps/client/src/scenes/game/application/BombManager.ts b/apps/client/src/scenes/game/application/BombManager.ts
index 0d1c8f4..b9caeb8 100644
--- a/apps/client/src/scenes/game/application/BombManager.ts
+++ b/apps/client/src/scenes/game/application/BombManager.ts
@@ -5,6 +5,7 @@
  */
 import type { Container } from "pixi.js";
 import { config } from "@client/config";
+import type { BombPlacedPayload } from "@repo/shared";
 import { LocalPlayerController } from "@client/scenes/game/entities/player/PlayerController";
 import { BombController } from "@client/scenes/game/entities/bomb/BombController";
 import type { GamePlayers } from "./game.types";
@@ -13,11 +14,19 @@
 export type ElapsedMsProvider = () => number;
 
 /** 爆弾の追加更新に使う入力データ型 */
-export type BombUpsertPayload = {
-  x: number;
-  y: number;
-  radiusGrid: number;
-  explodeAtElapsedMs: number;
+export type BombUpsertPayload = BombPlacedPayload & {
+  radiusGrid?: number;
+};
+
+/** 爆弾設置時に返す結果型 */
+export type BombPlacementResult = {
+  bombId: string;
+  payload: BombPlacedPayload;
+};
+
+/** 爆弾ペイロードから一意キーを生成する */
+export const createBombIdFromPayload = (payload: BombPlacedPayload): string => {
+  return `${payload.x}:${payload.y}:${payload.explodeAtElapsedMs}`;
 };
 
 type BombManagerOptions = {
@@ -34,7 +43,6 @@
   private myId: string;
   private getElapsedMs: ElapsedMsProvider;
   private bombs = new Map<string, BombController>();
-  private nextLocalBombId = 1;
   private lastBombPlacedElapsedMs = Number.NEGATIVE_INFINITY;
 
   constructor({ worldContainer, players, myId, getElapsedMs }: BombManagerOptions) {
@@ -45,29 +53,30 @@
   }
 
   /** 自プレイヤー位置に爆弾を設置し，生成IDを返す */
-  public placeBomb(): string | null {
+  public placeBomb(): BombPlacementResult | null {
     const me = this.players[this.myId];
     if (!me || !(me instanceof LocalPlayerController)) return null;
 
     const elapsedMs = this.getElapsedMs();
-    const { BOMB_COOLDOWN_MS, BOMB_FUSE_MS, BOMB_RADIUS_GRID } = config.GAME_CONFIG;
+    const { BOMB_COOLDOWN_MS, BOMB_FUSE_MS } = config.GAME_CONFIG;
     if (elapsedMs - this.lastBombPlacedElapsedMs < BOMB_COOLDOWN_MS) {
       return null;
     }
 
     const position = me.getPosition();
-    const payload: BombUpsertPayload = {
+    const payload: BombPlacedPayload = {
       x: position.x,
       y: position.y,
-      radiusGrid: BOMB_RADIUS_GRID,
       explodeAtElapsedMs: elapsedMs + BOMB_FUSE_MS,
     };
-    const bombId = `local-${this.nextLocalBombId}`;
-    this.nextLocalBombId += 1;
+    const bombId = createBombIdFromPayload(payload);
 
     this.upsertBomb(bombId, payload);
     this.lastBombPlacedElapsedMs = elapsedMs;
-    return bombId;
+    return {
+      bombId,
+      payload,
+    };
   }
 
   /** 指定IDの爆弾を追加または更新する */
@@ -78,7 +87,12 @@
       current.destroy();
     }
 
-    const bomb = new BombController(payload);
+    const resolvedPayload = {
+      ...payload,
+      radiusGrid: payload.radiusGrid ?? config.GAME_CONFIG.BOMB_RADIUS_GRID,
+    };
+
+    const bomb = new BombController(resolvedPayload);
     this.bombs.set(bombId, bomb);
     this.worldContainer.addChild(bomb.getDisplayObject());
   }
diff --git a/apps/client/src/scenes/game/application/GameNetworkSync.ts b/apps/client/src/scenes/game/application/GameNetworkSync.ts
index fc29a67..8cb19a4 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 {
+  BombPlacedPayload,
   CurrentPlayersPayload,
   GameStartPayload,
   NewPlayerPayload,
@@ -26,6 +27,7 @@
   gameMap: GameMapController;
   onGameStart: (startTime: number) => void;
   onGameEnd: () => void;
+  onBombPlaced: (payload: BombPlacedPayload) => 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 */
@@ -36,6 +38,7 @@
   private gameMap: GameMapController;
   private onGameStart: (startTime: number) => void;
   private onGameEnd: () => void;
+  private onBombPlaced: (payload: BombPlacedPayload) => void;
   private isBound = false;
 
   private debugLog = (message: string) => {
@@ -96,13 +99,18 @@
     this.onGameEnd();
   };
 
-  constructor({ worldContainer, players, myId, gameMap, onGameStart, onGameEnd }: GameNetworkSyncOptions) {
+  private handleBombPlaced = (payload: BombPlacedPayload) => {
+    this.onBombPlaced(payload);
+  };
+
+  constructor({ worldContainer, players, myId, gameMap, onGameStart, onGameEnd, onBombPlaced }: GameNetworkSyncOptions) {
     this.worldContainer = worldContainer;
     this.players = players;
     this.myId = myId;
     this.gameMap = gameMap;
     this.onGameStart = onGameStart;
     this.onGameEnd = onGameEnd;
+    this.onBombPlaced = onBombPlaced;
   }
 
   public bind() {
@@ -115,6 +123,7 @@
     socketManager.game.onRemovePlayer(this.handleRemovePlayer);
     socketManager.game.onUpdateMapCells(this.handleUpdateMapCells);
     socketManager.game.onGameEnd(this.handleGameEnd);
+    socketManager.game.onBombPlaced(this.handleBombPlaced);
 
     this.isBound = true;
   }
@@ -129,6 +138,7 @@
     socketManager.game.offRemovePlayer(this.handleRemovePlayer);
     socketManager.game.offUpdateMapCells(this.handleUpdateMapCells);
     socketManager.game.offGameEnd(this.handleGameEnd);
+    socketManager.game.offBombPlaced(this.handleBombPlaced);
 
     this.isBound = false;
   }
diff --git a/apps/server/src/logging/contracts/payloadByScope.ts b/apps/server/src/logging/contracts/payloadByScope.ts
index 8bb3fb5..f0ec8b1 100644
--- a/apps/server/src/logging/contracts/payloadByScope.ts
+++ b/apps/server/src/logging/contracts/payloadByScope.ts
@@ -46,13 +46,21 @@
   socketId: string;
 };
 
+/** NetworkのPLACE_BOMB不正ペイロードログ契約 */
+type NetworkPlaceBombLogPayload = {
+  event: typeof protocol.SocketEvents.PLACE_BOMB;
+  result: typeof logResults.IGNORED_INVALID_PAYLOAD;
+  socketId: string;
+};
+
 /** Networkスコープのログ契約ユニオン */
 type NetworkLogPayload =
   | NetworkConnectLogPayload
   | NetworkDisconnectLogPayload
   | NetworkJoinRoomLogPayload
   | NetworkPingLogPayload
-  | NetworkMoveLogPayload;
+  | NetworkMoveLogPayload
+  | NetworkPlaceBombLogPayload;
 
 /** GameUseCaseのSTART_GAMEログ契約 */
 type GameUseCaseStartGameLogPayload = {
diff --git a/apps/server/src/network/handlers/game/registerGameHandlers.ts b/apps/server/src/network/handlers/game/registerGameHandlers.ts
index b7bd305..97052ea 100644
--- a/apps/server/src/network/handlers/game/registerGameHandlers.ts
+++ b/apps/server/src/network/handlers/game/registerGameHandlers.ts
@@ -16,7 +16,7 @@
 import { movePlayerUseCase } from "@server/domains/game/application/useCases/movePlayerUseCase";
 import { pingUseCase } from "@server/domains/game/application/useCases/pingUseCase";
 import { createCommonHandlerContext } from "@server/network/handlers/CommonHandler";
-import { isMovePayload, isPingPayload } from "@server/network/validation/socketPayloadValidators";
+import { isBombPlacedPayload, isMovePayload, isPingPayload } from "@server/network/validation/socketPayloadValidators";
 import { createServerSocketOnBridge } from "@server/network/handlers/socketEventBridge";
 import { createPayloadGuard } from "@server/network/handlers/payloadGuard";
 import { createGameOutputAdapter } from "./createGameOutputAdapter";
@@ -25,6 +25,7 @@
 const gamePayloadValidators = {
   [protocol.SocketEvents.PING]: isPingPayload,
   [protocol.SocketEvents.MOVE]: isMovePayload,
+  [protocol.SocketEvents.PLACE_BOMB]: isBombPlacedPayload,
 } as const;
 
 /** ゲームイベントの購読とユースケース呼び出しを設定する */
@@ -46,6 +47,10 @@
     protocol.SocketEvents.MOVE,
     gamePayloadValidators[protocol.SocketEvents.MOVE]
   );
+  const guardPlaceBombPayload = guardOnEvent(
+    protocol.SocketEvents.PLACE_BOMB,
+    gamePayloadValidators[protocol.SocketEvents.PLACE_BOMB]
+  );
 
   // 遅延計測用のPINGを検証しPONGを返す
   onEvent(protocol.SocketEvents.PING, (clientTime) => {
@@ -91,4 +96,18 @@
       move: data,
     });
   });
+
+  // 爆弾設置入力を検証し，所属ルームへ同期配信する
+  onEvent(protocol.SocketEvents.PLACE_BOMB, (data) => {
+    if (!guardPlaceBombPayload(data)) {
+      return;
+    }
+
+    const roomId = roomManager.getRoomByPlayerId(socket.id)?.roomId;
+    if (!roomId) {
+      return;
+    }
+
+    common.emitToRoom(roomId, protocol.SocketEvents.BOMB_PLACED, data);
+  });
 };
diff --git a/apps/server/src/network/handlers/payloadGuard.ts b/apps/server/src/network/handlers/payloadGuard.ts
index dc308c4..5bacded 100644
--- a/apps/server/src/network/handlers/payloadGuard.ts
+++ b/apps/server/src/network/handlers/payloadGuard.ts
@@ -10,7 +10,8 @@
 type PayloadGuardEventName =
   | typeof protocol.SocketEvents.JOIN_ROOM
   | typeof protocol.SocketEvents.PING
-  | typeof protocol.SocketEvents.MOVE;
+  | typeof protocol.SocketEvents.MOVE
+  | typeof protocol.SocketEvents.PLACE_BOMB;
 type EventBoundPayloadGuard<TPayload> = (payload: unknown) => payload is TPayload;
 
 /**
@@ -50,6 +51,14 @@
           socketId,
         });
         break;
+
+      case protocol.SocketEvents.PLACE_BOMB:
+        logEvent(logScopes.NETWORK, {
+          event: protocol.SocketEvents.PLACE_BOMB,
+          result: logResults.IGNORED_INVALID_PAYLOAD,
+          socketId,
+        });
+        break;
     }
 
     return false;
diff --git a/apps/server/src/network/validation/socketPayloadValidators.ts b/apps/server/src/network/validation/socketPayloadValidators.ts
index 0345b37..ceae7ba 100644
--- a/apps/server/src/network/validation/socketPayloadValidators.ts
+++ b/apps/server/src/network/validation/socketPayloadValidators.ts
@@ -2,7 +2,7 @@
  * socketPayloadValidators
  * ソケット受信ペイロードの型ガードを提供する
  */
-import type { playerTypes, roomTypes } from "@repo/shared";
+import type { playerTypes, roomTypes, BombPlacedPayload } from "@repo/shared";
 import type { PingPayload } from "@repo/shared";
 
 const isFiniteNumber = (value: unknown): value is number => {
@@ -28,6 +28,20 @@
   return isFiniteNumber(candidate.x) && isFiniteNumber(candidate.y);
 };
 
+/** PLACE_BOMBイベントのペイロードが爆弾情報であるか判定する */
+export const isBombPlacedPayload = (value: unknown): value is BombPlacedPayload => {
+  if (typeof value !== "object" || value === null) {
+    return false;
+  }
+
+  const candidate = value as Record<string, unknown>;
+  return (
+    isFiniteNumber(candidate.x)
+    && isFiniteNumber(candidate.y)
+    && isFiniteNumber(candidate.explodeAtElapsedMs)
+  );
+};
+
 /** JOIN_ROOMイベントのペイロードが参加情報であるか判定する */
 export const isJoinRoomPayload = (value: unknown): value is roomTypes.JoinRoomPayload => {
   if (typeof value !== "object" || value === null) {