diff --git a/apps/client/src/scenes/game/application/GameLoop.ts b/apps/client/src/scenes/game/application/GameLoop.ts
index 74d807f..4fc4139 100644
--- a/apps/client/src/scenes/game/application/GameLoop.ts
+++ b/apps/client/src/scenes/game/application/GameLoop.ts
@@ -8,6 +8,7 @@
 import { LocalPlayerController } from "@client/scenes/game/entities/player/PlayerController";
 import { BombManager } from "@client/scenes/game/entities/bomb/BombManager";
 import type { GamePlayers } from "./game.types";
+import { PlayerRepository } from "./player/PlayerRepository";
 import { InputStep } from "./loopSteps/InputStep";
 import { SimulationStep } from "./loopSteps/SimulationStep";
 import { CameraStep } from "./loopSteps/CameraStep";
@@ -30,7 +31,7 @@
 export class GameLoop {
   private app: Application;
   private worldContainer: Container;
-  private players: GamePlayers;
+  private playerRepository: PlayerRepository;
   private myId: string;
   private inputStep: InputStep;
   private simulationStep: SimulationStep;
@@ -41,7 +42,7 @@
   constructor({ app, worldContainer, players, myId, getJoystickInput, bombManager, moveSender }: GameLoopOptions) {
     this.app = app;
     this.worldContainer = worldContainer;
-    this.players = players;
+    this.playerRepository = new PlayerRepository(players);
     this.myId = myId;
     this.inputStep = new InputStep({ getJoystickInput });
     this.simulationStep = new SimulationStep({
@@ -58,7 +59,7 @@
   }
 
   public tick = (ticker: Ticker) => {
-    const me = this.players[this.myId];
+    const me = this.playerRepository.getById(this.myId);
     if (!me || !(me instanceof LocalPlayerController)) return;
 
     const { deltaSeconds } = resolveFrameDelta(
@@ -68,7 +69,7 @@
     const frameContext: LoopFrameContext = {
       app: this.app,
       worldContainer: this.worldContainer,
-      players: this.players,
+      playerRepository: this.playerRepository,
       me,
       deltaSeconds,
       isMoving: false,
diff --git a/apps/client/src/scenes/game/application/GameNetworkSync.ts b/apps/client/src/scenes/game/application/GameNetworkSync.ts
index 198f43d..bc3318f 100644
--- a/apps/client/src/scenes/game/application/GameNetworkSync.ts
+++ b/apps/client/src/scenes/game/application/GameNetworkSync.ts
@@ -22,6 +22,7 @@
   toRemoteBombPlacedPayload,
   toRemotePlayerDeadPayload,
 } from "./network/adapters/GameNetworkEventAdapter";
+import { PlayerRepository } from "./player/PlayerRepository";
 import { PlayerSyncHandler } from "./network/handlers/PlayerSyncHandler";
 import { MapSyncHandler } from "./network/handlers/MapSyncHandler";
 import { CombatSyncHandler } from "./network/handlers/CombatSyncHandler";
@@ -44,6 +45,7 @@
 
 /** 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 */
 export class GameNetworkSync {
+  private readonly playerRepository: PlayerRepository;
   private playerSyncHandler: PlayerSyncHandler;
   private mapSyncHandler: MapSyncHandler;
   private combatSyncHandler: CombatSyncHandler;
@@ -84,9 +86,10 @@
     onBombPlacementAcknowledged,
     onRemotePlayerDead,
   }: GameNetworkSyncOptions) {
+    this.playerRepository = new PlayerRepository(players);
     this.playerSyncHandler = new PlayerSyncHandler({
       worldContainer,
-      players,
+      playerRepository: this.playerRepository,
       myId,
       appearanceResolver,
     });
diff --git a/apps/client/src/scenes/game/application/loopSteps/LoopStep.ts b/apps/client/src/scenes/game/application/loopSteps/LoopStep.ts
index f94e9c4..2e3c883 100644
--- a/apps/client/src/scenes/game/application/loopSteps/LoopStep.ts
+++ b/apps/client/src/scenes/game/application/loopSteps/LoopStep.ts
@@ -5,13 +5,13 @@
  */
 import type { Application, Container } from "pixi.js";
 import type { LocalPlayerController } from "@client/scenes/game/entities/player/PlayerController";
-import type { GamePlayers } from "@client/scenes/game/application/game.types";
+import type { PlayerRepository } from "@client/scenes/game/application/player/PlayerRepository";
 
 /** 1フレーム分の更新文脈を表す型 */
 export type LoopFrameContext = {
   app: Application;
   worldContainer: Container;
-  players: GamePlayers;
+  playerRepository: PlayerRepository;
   me: LocalPlayerController;
   deltaSeconds: number;
   isMoving: boolean;
diff --git a/apps/client/src/scenes/game/application/loopSteps/SimulationStep.ts b/apps/client/src/scenes/game/application/loopSteps/SimulationStep.ts
index 2f5a34c..59beed9 100644
--- a/apps/client/src/scenes/game/application/loopSteps/SimulationStep.ts
+++ b/apps/client/src/scenes/game/application/loopSteps/SimulationStep.ts
@@ -6,7 +6,7 @@
 import { config } from "@client/config";
 import { LocalPlayerController, RemotePlayerController } from "@client/scenes/game/entities/player/PlayerController";
 import type { MoveSender } from "@client/scenes/game/application/network/PlayerMoveSender";
-import type { GamePlayers } from "../game.types";
+import type { PlayerRepository } from "../player/PlayerRepository";
 import type { LoopFrameContext, LoopStep } from "./LoopStep";
 
 /** SimulationStep の初期化入力 */
@@ -17,7 +17,7 @@
 
 type SimulationStepParams = {
   me: LocalPlayerController;
-  players: GamePlayers;
+  playerRepository: PlayerRepository;
   deltaSeconds: number;
   isMoving: boolean;
 };
@@ -38,13 +38,16 @@
   public run(context: LoopFrameContext): void {
     const params: SimulationStepParams = {
       me: context.me,
-      players: context.players,
+      playerRepository: context.playerRepository,
       deltaSeconds: context.deltaSeconds,
       isMoving: context.isMoving,
     };
 
     this.runLocalSimulation({ me: params.me, isMoving: params.isMoving });
-    this.runRemoteSimulation({ players: params.players, deltaSeconds: params.deltaSeconds });
+    this.runRemoteSimulation({
+      playerRepository: params.playerRepository,
+      deltaSeconds: params.deltaSeconds,
+    });
   }
 
   private runLocalSimulation({ me, isMoving }: Pick<SimulationStepParams, "me" | "isMoving">) {
@@ -68,8 +71,8 @@
     this.wasMoving = isMoving;
   }
 
-  private runRemoteSimulation({ players, deltaSeconds }: Pick<SimulationStepParams, "players" | "deltaSeconds">) {
-    Object.values(players).forEach((player) => {
+  private runRemoteSimulation({ playerRepository, deltaSeconds }: Pick<SimulationStepParams, "playerRepository" | "deltaSeconds">) {
+    playerRepository.values().forEach((player) => {
       if (player instanceof RemotePlayerController) {
         player.tick(deltaSeconds);
       }
diff --git a/apps/client/src/scenes/game/application/network/handlers/PlayerSyncHandler.ts b/apps/client/src/scenes/game/application/network/handlers/PlayerSyncHandler.ts
index a1556db..084fe8d 100644
--- a/apps/client/src/scenes/game/application/network/handlers/PlayerSyncHandler.ts
+++ b/apps/client/src/scenes/game/application/network/handlers/PlayerSyncHandler.ts
@@ -15,12 +15,12 @@
   RemotePlayerController,
 } from "@client/scenes/game/entities/player/PlayerController";
 import { AppearanceResolver } from "@client/scenes/game/application/AppearanceResolver";
-import type { GamePlayers } from "@client/scenes/game/application/game.types";
+import { PlayerRepository } from "@client/scenes/game/application/player/PlayerRepository";
 
 /** PlayerSyncHandler の初期化入力 */
 export type PlayerSyncHandlerOptions = {
   worldContainer: Container;
-  players: GamePlayers;
+  playerRepository: PlayerRepository;
   myId: string;
   appearanceResolver: AppearanceResolver;
 };
@@ -28,13 +28,13 @@
 /** プレイヤー関連の同期イベント適用を担当する */
 export class PlayerSyncHandler {
   private readonly worldContainer: Container;
-  private readonly players: GamePlayers;
+  private readonly playerRepository: PlayerRepository;
   private readonly myId: string;
   private readonly appearanceResolver: AppearanceResolver;
 
-  constructor({ worldContainer, players, myId, appearanceResolver }: PlayerSyncHandlerOptions) {
+  constructor({ worldContainer, playerRepository, myId, appearanceResolver }: PlayerSyncHandlerOptions) {
     this.worldContainer = worldContainer;
-    this.players = players;
+    this.playerRepository = playerRepository;
     this.myId = myId;
     this.appearanceResolver = appearanceResolver;
   }
@@ -46,7 +46,7 @@
         ? new LocalPlayerController(player, this.appearanceResolver)
         : new RemotePlayerController(player, this.appearanceResolver);
       this.worldContainer.addChild(playerController.getDisplayObject());
-      this.players[player.id] = playerController;
+      this.playerRepository.upsert(player.id, playerController);
     });
   };
 
@@ -54,13 +54,13 @@
   public handleNewPlayer = (payload: NewPlayerPayload): void => {
     const playerController = new RemotePlayerController(payload, this.appearanceResolver);
     this.worldContainer.addChild(playerController.getDisplayObject());
-    this.players[payload.id] = playerController;
+    this.playerRepository.upsert(payload.id, playerController);
   };
 
   /** プレイヤー差分更新を反映する */
   public handlePlayerUpdates = (changedPlayers: UpdatePlayersPayload): void => {
     changedPlayers.forEach((playerData) => {
-      const target = this.players[playerData.id];
+      const target = this.playerRepository.getById(playerData.id);
       if (target && target instanceof RemotePlayerController) {
         target.applyRemoteUpdate({ x: playerData.x, y: playerData.y });
       }
@@ -69,13 +69,12 @@
 
   /** 退出プレイヤーを削除する */
   public handleRemovePlayer = (id: RemovePlayerPayload): void => {
-    const target = this.players[id];
+    const target = this.playerRepository.remove(id);
     if (!target) {
       return;
     }
 
     this.worldContainer.removeChild(target.getDisplayObject());
     target.destroy();
-    delete this.players[id];
   };
 }
\ No newline at end of file
diff --git a/apps/client/src/scenes/game/application/player/PlayerRepository.ts b/apps/client/src/scenes/game/application/player/PlayerRepository.ts
new file mode 100644
index 0000000..cb51025
--- /dev/null
+++ b/apps/client/src/scenes/game/application/player/PlayerRepository.ts
@@ -0,0 +1,49 @@
+/**
+ * PlayerRepository
+ * プレイヤー集合の更新窓口を提供する
+ * 参照と更新を集約して副作用の追跡を容易にする
+ */
+import type {
+  GamePlayerController,
+  GamePlayers,
+} from "@client/scenes/game/application/game.types";
+
+/** プレイヤー集合の更新と参照を管理するリポジトリ */
+export class PlayerRepository {
+  private readonly players: GamePlayers;
+
+  constructor(players: GamePlayers = {}) {
+    this.players = players;
+  }
+
+  /** プレイヤーIDでコントローラーを取得する */
+  public getById(playerId: string): GamePlayerController | undefined {
+    return this.players[playerId];
+  }
+
+  /** プレイヤーを追加または更新する */
+  public upsert(playerId: string, controller: GamePlayerController): void {
+    this.players[playerId] = controller;
+  }
+
+  /** プレイヤーを削除して削除対象を返す */
+  public remove(playerId: string): GamePlayerController | undefined {
+    const target = this.players[playerId];
+    if (!target) {
+      return undefined;
+    }
+
+    delete this.players[playerId];
+    return target;
+  }
+
+  /** 管理中プレイヤー配列を返す */
+  public values(): GamePlayerController[] {
+    return Object.values(this.players);
+  }
+
+  /** 内部で保持するプレイヤー集合を返す */
+  public toRecord(): GamePlayers {
+    return this.players;
+  }
+}
\ No newline at end of file