diff --git a/apps/client/src/network/handlers/GameHandler.ts b/apps/client/src/network/handlers/GameHandler.ts
index 2d5b226..e87bf04 100644
--- a/apps/client/src/network/handlers/GameHandler.ts
+++ b/apps/client/src/network/handlers/GameHandler.ts
@@ -1,14 +1,20 @@
+/**
+ * GameHandler
+ * ゲーム関連のソケット購読と送信APIを提供する
+ * シーン層が利用する通信操作を集約する
+ */
 import type { Socket } from "socket.io-client";
 import { protocol } from "@repo/shared";
 import type { playerTypes, gridMapTypes } from "@repo/shared";
 
-type GameHandler = {
+/** ゲームシーンが利用するソケット操作の契約 */
+export type GameHandler = {
   onCurrentPlayers: (callback: (players: playerTypes.PlayerData[] | Record<string, playerTypes.PlayerData>) => void) => void;
   offCurrentPlayers: (callback: (players: playerTypes.PlayerData[] | Record<string, playerTypes.PlayerData>) => void) => void;
   onNewPlayer: (callback: (player: playerTypes.PlayerData) => void) => void;
   offNewPlayer: (callback: (player: playerTypes.PlayerData) => void) => void;
-  onUpdatePlayer: (callback: (data: Partial<playerTypes.PlayerData> & { id: string }) => void) => void;
-  offUpdatePlayer: (callback: (data: Partial<playerTypes.PlayerData> & { id: string }) => void) => void;
+  onUpdatePlayers: (callback: (players: playerTypes.PlayerData[]) => void) => void;
+  offUpdatePlayers: (callback: (players: playerTypes.PlayerData[]) => void) => void;
   onRemovePlayer: (callback: (id: string) => void) => void;
   offRemovePlayer: (callback: (id: string) => void) => void;
   onUpdateMapCells: (callback: (updates: gridMapTypes.CellUpdate[]) => void) => void;
@@ -19,6 +25,7 @@
   readyForGame: () => void;
 };
 
+/** ソケットインスタンスからゲーム向けハンドラを生成する */
 export const createGameHandler = (socket: Socket): GameHandler => {
   return {
     onCurrentPlayers: (callback) => {
@@ -33,11 +40,11 @@
     offNewPlayer: (callback) => {
       socket.off(protocol.SocketEvents.NEW_PLAYER, callback);
     },
-    onUpdatePlayer: (callback) => {
-      socket.on(protocol.SocketEvents.UPDATE_PLAYER, callback);
+    onUpdatePlayers: (callback) => {
+      socket.on(protocol.SocketEvents.UPDATE_PLAYERS, callback);
     },
-    offUpdatePlayer: (callback) => {
-      socket.off(protocol.SocketEvents.UPDATE_PLAYER, callback);
+    offUpdatePlayers: (callback) => {
+      socket.off(protocol.SocketEvents.UPDATE_PLAYERS, callback);
     },
     onRemovePlayer: (callback) => {
       socket.on(protocol.SocketEvents.REMOVE_PLAYER, callback);
@@ -66,5 +73,3 @@
     }
   };
 };
-
-export type { GameHandler };
diff --git a/apps/client/src/scenes/game/application/GameNetworkSync.ts b/apps/client/src/scenes/game/application/GameNetworkSync.ts
index a34e55f..6e7422a 100644
--- a/apps/client/src/scenes/game/application/GameNetworkSync.ts
+++ b/apps/client/src/scenes/game/application/GameNetworkSync.ts
@@ -49,12 +49,15 @@
     }
   };
 
-  private handleUpdatePlayer = (data: Partial<playerTypes.PlayerData> & { id: string }) => {
-    if (data.id === this.myId) return;
-    const target = this.players[data.id];
-    if (target && target instanceof RemotePlayerController) {
-      target.applyRemoteUpdate({ x: data.x, y: data.y });
-    }
+  private handleUpdatePlayers = (serverPlayers: playerTypes.PlayerData[]) => {
+    serverPlayers.forEach((playerData) => {
+      if (playerData.id === this.myId) return;
+
+      const target = this.players[playerData.id];
+      if (target && target instanceof RemotePlayerController) {
+        target.applyRemoteUpdate({ x: playerData.x, y: playerData.y });
+      }
+    });
   };
 
   private handleRemovePlayer = (id: string) => {
@@ -84,7 +87,7 @@
     socketManager.game.onCurrentPlayers(this.handleCurrentPlayers);
     socketManager.game.onNewPlayer(this.handleNewPlayer);
     socketManager.game.onGameStart(this.handleGameStart);
-    socketManager.game.onUpdatePlayer(this.handleUpdatePlayer);
+    socketManager.game.onUpdatePlayers(this.handleUpdatePlayers);
     socketManager.game.onRemovePlayer(this.handleRemovePlayer);
     socketManager.game.onUpdateMapCells(this.handleUpdateMapCells);
 
@@ -97,7 +100,7 @@
     socketManager.game.offCurrentPlayers(this.handleCurrentPlayers);
     socketManager.game.offNewPlayer(this.handleNewPlayer);
     socketManager.game.offGameStart(this.handleGameStart);
-    socketManager.game.offUpdatePlayer(this.handleUpdatePlayer);
+    socketManager.game.offUpdatePlayers(this.handleUpdatePlayers);
     socketManager.game.offRemovePlayer(this.handleRemovePlayer);
     socketManager.game.offUpdateMapCells(this.handleUpdateMapCells);
 
diff --git a/apps/server/src/application/coordinators/startGameCoordinator.ts b/apps/server/src/application/coordinators/startGameCoordinator.ts
index 87220ce..cddf474 100644
--- a/apps/server/src/application/coordinators/startGameCoordinator.ts
+++ b/apps/server/src/application/coordinators/startGameCoordinator.ts
@@ -17,7 +17,7 @@
   roomManager: StartGameRoomPort;
   output: Pick<
     GameOutputPort,
-    | "publishUpdatePlayerToRoom"
+    | "publishUpdatePlayersToRoom"
     | "publishMapCellUpdatesToRoom"
     | "publishGameEndToRoom"
     | "publishGameStartToRoom"
diff --git a/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts b/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
index c3f8e0f..4d03233 100644
--- a/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
+++ b/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
@@ -47,7 +47,10 @@
 /** ゲーム系ユースケースが利用する送信出力ポート */
 export interface GameOutputPort {
   publishPongToSocket(payload: { clientTime: number; serverTime: number }): void;
-  publishUpdatePlayerToRoom(roomId: roomTypes.Room["roomId"], playerData: playerTypes.PlayerData): void;
+  publishUpdatePlayersToRoom(
+    roomId: roomTypes.Room["roomId"],
+    players: playerTypes.PlayerData[]
+  ): void;
   publishMapCellUpdatesToRoom(
     roomId: roomTypes.Room["roomId"],
     cellUpdates: gridMapTypes.CellUpdate[]
diff --git a/apps/server/src/domains/game/application/useCases/startGameUseCase.ts b/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
index f4075f0..9f95b56 100644
--- a/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
+++ b/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
@@ -12,7 +12,7 @@
   onGameEnd: () => void;
   output: Pick<
     GameOutputPort,
-    | "publishUpdatePlayerToRoom"
+    | "publishUpdatePlayersToRoom"
     | "publishMapCellUpdatesToRoom"
     | "publishGameEndToRoom"
     | "publishGameStartToRoom"
@@ -31,9 +31,7 @@
     roomId,
     playerIds,
     (tickData) => {
-      tickData.players.forEach((playerData) => {
-        output.publishUpdatePlayerToRoom(roomId, playerData);
-      });
+      output.publishUpdatePlayersToRoom(roomId, tickData.players);
 
       if (tickData.cellUpdates.length > 0) {
         output.publishMapCellUpdatesToRoom(roomId, tickData.cellUpdates);
diff --git a/apps/server/src/network/handlers/game/createGameOutputAdapter.ts b/apps/server/src/network/handlers/game/createGameOutputAdapter.ts
index 98d1c63..4e43e44 100644
--- a/apps/server/src/network/handlers/game/createGameOutputAdapter.ts
+++ b/apps/server/src/network/handlers/game/createGameOutputAdapter.ts
@@ -14,7 +14,7 @@
 type PongPayload = { clientTime: number; serverTime: number };
 type GameStartPayload = { startTime: number };
 type CurrentPlayersPayload = playerTypes.PlayerData[];
-type UpdatePlayerPayload = playerTypes.PlayerData;
+type UpdatePlayersPayload = playerTypes.PlayerData[];
 type MapCellUpdatesPayload = gridMapTypes.CellUpdate[];
 
 /** ゲーム出力アダプターのインターフェース */
@@ -29,8 +29,8 @@
     publishPongToSocket: (payload: PongPayload) => {
       common.emitToSocket(protocol.SocketEvents.PONG, payload);
     },
-    publishUpdatePlayerToRoom: (roomId: RoomId, playerData: UpdatePlayerPayload) => {
-      common.emitToRoom(roomId, protocol.SocketEvents.UPDATE_PLAYER, playerData);
+    publishUpdatePlayersToRoom: (roomId: RoomId, players: UpdatePlayersPayload) => {
+      common.emitToRoom(roomId, protocol.SocketEvents.UPDATE_PLAYERS, players);
     },
     publishMapCellUpdatesToRoom: (roomId: RoomId, cellUpdates: MapCellUpdatesPayload) => {
       common.emitToRoom(roomId, protocol.SocketEvents.UPDATE_MAP_CELLS, cellUpdates);
diff --git a/packages/shared/src/protocol/events.ts b/packages/shared/src/protocol/events.ts
index 39a1c4a..6082e05 100644
--- a/packages/shared/src/protocol/events.ts
+++ b/packages/shared/src/protocol/events.ts
@@ -1,3 +1,9 @@
+/**
+ * events
+ * ソケット通信で利用するイベント名定数を定義する
+ * クライアントとサーバー間のイベント契約を共有する
+ */
+/** ソケットイベント名の一覧定数 */
 export const SocketEvents = {
   // 接続・切断イベント名
   CONNECT: "connect",
@@ -14,7 +20,8 @@
   // ゲームプレイ関連イベント名
   CURRENT_PLAYERS: "current_players",
   NEW_PLAYER: "new_player",
-  UPDATE_PLAYER: "update_player",
+  // 1ティック分のプレイヤー状態を配列でまとめて通知する
+  UPDATE_PLAYERS: "update_players",
   REMOVE_PLAYER: "remove_player",
   MOVE: "move",
   UPDATE_MAP_CELLS: "update_map_cells",