diff --git a/apps/client/src/scenes/game/application/GameNetworkSync.ts b/apps/client/src/scenes/game/application/GameNetworkSync.ts
index 0bf4f13..45b6e07 100644
--- a/apps/client/src/scenes/game/application/GameNetworkSync.ts
+++ b/apps/client/src/scenes/game/application/GameNetworkSync.ts
@@ -49,7 +49,7 @@
     }
   };
 
-  private handleUpdatePlayers = (changedPlayers: playerTypes.PlayerData[]) => {
+  private handlePlayerUpdates = (changedPlayers: playerTypes.PlayerData[]) => {
     // UPDATE_PLAYERS は差分のみ届くため，対象IDだけ上書き更新する
     changedPlayers.forEach((playerData) => {
       if (playerData.id === this.myId) return;
@@ -88,7 +88,7 @@
     socketManager.game.onCurrentPlayers(this.handleCurrentPlayers);
     socketManager.game.onNewPlayer(this.handleNewPlayer);
     socketManager.game.onGameStart(this.handleGameStart);
-    socketManager.game.onUpdatePlayers(this.handleUpdatePlayers);
+    socketManager.game.onUpdatePlayers(this.handlePlayerUpdates);
     socketManager.game.onRemovePlayer(this.handleRemovePlayer);
     socketManager.game.onUpdateMapCells(this.handleUpdateMapCells);
 
@@ -101,7 +101,7 @@
     socketManager.game.offCurrentPlayers(this.handleCurrentPlayers);
     socketManager.game.offNewPlayer(this.handleNewPlayer);
     socketManager.game.offGameStart(this.handleGameStart);
-    socketManager.game.offUpdatePlayers(this.handleUpdatePlayers);
+    socketManager.game.offUpdatePlayers(this.handlePlayerUpdates);
     socketManager.game.offRemovePlayer(this.handleRemovePlayer);
     socketManager.game.offUpdateMapCells(this.handleUpdateMapCells);
 
diff --git a/apps/server/src/domains/game/application/services/GamePlayerOperationService.ts b/apps/server/src/domains/game/application/services/GamePlayerOperationService.ts
index e00cf54..9874b80 100644
--- a/apps/server/src/domains/game/application/services/GamePlayerOperationService.ts
+++ b/apps/server/src/domains/game/application/services/GamePlayerOperationService.ts
@@ -42,20 +42,15 @@
       return;
     }
 
+    const roomPlayerSet = this.roomToPlayers.get(roomId);
     const session = this.sessions.get(roomId);
     if (!session) {
-      this.playerToRoom.delete(id);
-      this.roomToPlayers.get(roomId)?.delete(id);
-
-      if (this.roomToPlayers.get(roomId)?.size === 0) {
-        this.roomToPlayers.delete(roomId);
-      }
+      this.removePlayerFromIndexes(roomId, id, roomPlayerSet);
       return;
     }
 
     const removed = session.removePlayer(id);
-    this.playerToRoom.delete(id);
-    this.roomToPlayers.get(roomId)?.delete(id);
+    this.removePlayerFromIndexes(roomId, id, roomPlayerSet);
 
     if (removed && session.isEmpty()) {
       session.dispose();
@@ -69,4 +64,21 @@
       });
     }
   }
+
+  private removePlayerFromIndexes(
+    roomId: string,
+    playerId: string,
+    roomPlayerSet: Set<string> | undefined
+  ): void {
+    this.playerToRoom.delete(playerId);
+
+    if (!roomPlayerSet) {
+      return;
+    }
+
+    roomPlayerSet.delete(playerId);
+    if (roomPlayerSet.size === 0) {
+      this.roomToPlayers.delete(roomId);
+    }
+  }
 }
\ No newline at end of file
diff --git a/apps/server/src/domains/game/application/useCases/startGameUseCase.ts b/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
index c3a31d2..d6e871f 100644
--- a/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
+++ b/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
@@ -31,8 +31,8 @@
     roomId,
     playerIds,
     (tickData) => {
-      if (tickData.players.length > 0) {
-        output.publishUpdatePlayersToRoom(roomId, tickData.players);
+      if (tickData.playerUpdates.length > 0) {
+        output.publishUpdatePlayersToRoom(roomId, tickData.playerUpdates);
       }
 
       if (tickData.cellUpdates.length > 0) {
diff --git a/apps/server/src/domains/game/loop/GameLoop.ts b/apps/server/src/domains/game/loop/GameLoop.ts
index 18aa1d5..e34af53 100644
--- a/apps/server/src/domains/game/loop/GameLoop.ts
+++ b/apps/server/src/domains/game/loop/GameLoop.ts
@@ -12,7 +12,7 @@
 // コールバックで渡すデータの型定義
 /** 1ティック分のプレイヤー情報とマップ差分を表すデータ */
 export interface TickData {
-  players: {
+  playerUpdates: {
     id: string;
     x: number;
     y: number;
@@ -29,7 +29,7 @@
   private endMonotonicTimeMs: number = 0;
   private nextTickAtMs: number = 0;
   private readonly maxCatchUpTicks: number = 3;
-  private lastSentPlayers: Map<string, TickData["players"][number]> = new Map();
+  private lastSentPlayers: Map<string, TickData["playerUpdates"][number]> = new Map();
 
   constructor(
     private roomId: string,
@@ -103,7 +103,7 @@
   }
 
   private processSingleTick(): void {
-    const changedPlayers: TickData["players"] = [];
+    const changedPlayers: TickData["playerUpdates"] = [];
 
     // 1. 各プレイヤーの座標処理とマス塗りの判定
     this.players.forEach((player) => {
@@ -146,7 +146,7 @@
 
     // 3. 通信層（GameHandler）へデータを渡す
     this.onTick({
-      players: changedPlayers,
+      playerUpdates: changedPlayers,
       cellUpdates: cellUpdates,
     });
   }