diff --git a/apps/server/src/domains/game/GameLoop.ts b/apps/server/src/domains/game/GameLoop.ts
deleted file mode 100644
index 1838556..0000000
--- a/apps/server/src/domains/game/GameLoop.ts
+++ /dev/null
@@ -1,100 +0,0 @@
-import { Player } from "./entities/player/Player.js";
-import { MapStore } from "./entities/map/MapStore";
-import { getPlayerGridIndex } from "./entities/player/playerPosition.js";
-import { config } from "@repo/shared";
-import type { gridMapTypes } from "@repo/shared";
-import { logEvent } from "@server/logging/logEvent";
-
-// コールバックで渡すデータの型定義
-export interface TickData {
-  players: {
-    id: string;
-    x: number;
-    y: number;
-    teamId: number;
-  }[];
-  cellUpdates: gridMapTypes.CellUpdate[];
-}
-
-export class GameLoop {
-  private loopId: NodeJS.Timeout | null = null;
-  private startTime: number = 0;
-
-  constructor(
-    private roomId: string,
-    private tickRate: number,
-    private playerIds: string[],
-    private players: Map<string, Player>,
-    private mapStore: MapStore,
-    private onTick: (data: TickData) => void,
-    private onGameEnd: () => void   // ゲーム終了時のコールバック
-  ) {}
-
-  start() {
-    // 既にループが回っている場合は何もしない
-    if (this.loopId) return;
-
-    this.startTime = Date.now();
-
-    this.loopId = setInterval(() => {
-      // 時間経過のチェック
-      const elapsedTimeMs = Date.now() - this.startTime;
-      if (elapsedTimeMs >= config.GAME_CONFIG.GAME_DURATION_SEC * 1000) {
-        // ゲーム終了時にループを止めて終了処理へ
-        this.stop();
-        this.onGameEnd();
-        return; // 今回のフレームの座標更新はスキップ
-      }
-
-      const playersData: TickData["players"] = [];
-
-      // 1. 各プレイヤーの座標処理とマス塗りの判定
-      this.playerIds.forEach(id => {
-        const player = this.players.get(id);
-        if (!player) return;
-
-        const gridIndex = getPlayerGridIndex(player);
-        if (gridIndex !== null) {
-          this.mapStore.paintCell(gridIndex, player.teamId);
-        }
-
-        // 送信用のプレイヤーデータを構築
-        playersData.push({
-          id: player.id,
-          x: player.x,
-          y: player.y,
-          teamId: player.teamId,
-        });
-      });
-
-      // 2. マスの差分（Diff）を取得
-      const cellUpdates = this.mapStore.getAndClearUpdates();
-
-      // 3. 通信層（GameHandler）へデータを渡す
-      this.onTick({
-        players: playersData,
-        cellUpdates: cellUpdates,
-      });
-      
-    }, this.tickRate);
-
-    logEvent("GameLoop", {
-      event: "GAME_LOOP",
-      result: "started",
-      roomId: this.roomId,
-      tickRate: this.tickRate,
-    });
-  }
-
-  stop() {
-    if (this.loopId) {
-      clearInterval(this.loopId);
-      this.loopId = null;
-      logEvent("GameLoop", {
-        event: "GAME_LOOP",
-        result: "stopped",
-        roomId: this.roomId,
-      });
-    }
-  }
-}
\ No newline at end of file
diff --git a/apps/server/src/domains/game/GameManager.ts b/apps/server/src/domains/game/GameManager.ts
index cf8725f..799d858 100644
--- a/apps/server/src/domains/game/GameManager.ts
+++ b/apps/server/src/domains/game/GameManager.ts
@@ -1,4 +1,4 @@
-import { type TickData } from "./GameLoop";
+import { type TickData } from "./loop/GameLoop";
 import { Player } from "./entities/player/Player.js";
 import { GameSessionService } from "./application/services/GameSessionService";
 
diff --git a/apps/server/src/domains/game/GameSessionManager.ts b/apps/server/src/domains/game/GameSessionManager.ts
index ebd6505..0606222 100644
--- a/apps/server/src/domains/game/GameSessionManager.ts
+++ b/apps/server/src/domains/game/GameSessionManager.ts
@@ -1,4 +1,4 @@
-import { type TickData } from "./GameLoop";
+import { type TickData } from "./loop/GameLoop";
 import { Player } from "./entities/player/Player.js";
 import { GameSessionService } from "./application/services/GameSessionService";
 
diff --git a/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts b/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
index 7cdb2d0..2686513 100644
--- a/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
+++ b/apps/server/src/domains/game/application/ports/gameUseCasePorts.ts
@@ -1,4 +1,4 @@
-import type { TickData } from "../../GameLoop";
+import type { TickData } from "../../loop/GameLoop";
 import type { playerTypes } from "@repo/shared";
 
 export interface StartGamePort {
diff --git a/apps/server/src/domains/game/application/services/GameRoomSession.ts b/apps/server/src/domains/game/application/services/GameRoomSession.ts
index 302fda2..4ac08b7 100644
--- a/apps/server/src/domains/game/application/services/GameRoomSession.ts
+++ b/apps/server/src/domains/game/application/services/GameRoomSession.ts
@@ -1,5 +1,5 @@
 import { logEvent } from "@server/logging/logEvent";
-import { GameLoop, type TickData } from "../../GameLoop";
+import { GameLoop, type TickData } from "../../loop/GameLoop";
 import { Player } from "../../entities/player/Player.js";
 import { MapStore } from "../../entities/map/MapStore";
 import { createSpawnedPlayer } from "../../entities/player/playerSpawn.js";
diff --git a/apps/server/src/domains/game/application/services/GameSessionService.ts b/apps/server/src/domains/game/application/services/GameSessionService.ts
index 634ac0a..020282b 100644
--- a/apps/server/src/domains/game/application/services/GameSessionService.ts
+++ b/apps/server/src/domains/game/application/services/GameSessionService.ts
@@ -1,5 +1,5 @@
 import { config } from "@repo/shared";
-import { type TickData } from "../../GameLoop";
+import { type TickData } from "../../loop/GameLoop";
 import { logEvent } from "@server/logging/logEvent";
 import { GameRoomSession } from "./GameRoomSession";
 
diff --git a/apps/server/src/domains/game/entities/map/MapStore.ts b/apps/server/src/domains/game/entities/map/MapStore.ts
index a23f0ff..15b03f8 100644
--- a/apps/server/src/domains/game/entities/map/MapStore.ts
+++ b/apps/server/src/domains/game/entities/map/MapStore.ts
@@ -1,6 +1,8 @@
 // apps/server/src/domains/game/entities/map/MapStore.ts
 import type { gridMapTypes } from "@repo/shared";
-import { config } from "@repo/shared";
+import { createInitialGridColors } from "./mapGrid.js";
+import { paintCellIfChanged } from "./mapPainting.js";
+import { drainPendingUpdates } from "./mapUpdates.js";
 
 export class MapStore {
   // 全マスの現在の色（teamId）を保持
@@ -10,8 +12,7 @@
 
   constructor() {
     // 初期状態は -1 (無色) などで初期化
-    const totalCells = config.GAME_CONFIG.GRID_COLS * config.GAME_CONFIG.GRID_ROWS;
-    this.gridColors = new Array(totalCells).fill(-1);
+    this.gridColors = createInitialGridColors();
     this.pendingUpdates = [];
   }
 
@@ -19,18 +20,18 @@
    * マスを塗り、色が変化した場合のみ差分キューに追加する
    */
   public paintCell(index: number, teamId: number): void {
-    if (this.gridColors[index] !== teamId) {
-      this.gridColors[index] = teamId;
-      this.pendingUpdates.push({ index, teamId });
-    }
+    paintCellIfChanged({
+      gridColors: this.gridColors,
+      pendingUpdates: this.pendingUpdates,
+      index,
+      teamId,
+    });
   }
 
   /**
    * 溜まっている差分を取得し、キューをクリアする（ループ送信時に使用）
    */
   public getAndClearUpdates(): gridMapTypes.CellUpdate[] {
-    const updates = [...this.pendingUpdates];
-    this.pendingUpdates = [];
-    return updates;
+    return drainPendingUpdates(this.pendingUpdates);
   }
 }
\ No newline at end of file
diff --git a/apps/server/src/domains/game/entities/map/mapGrid.ts b/apps/server/src/domains/game/entities/map/mapGrid.ts
new file mode 100644
index 0000000..c08cc21
--- /dev/null
+++ b/apps/server/src/domains/game/entities/map/mapGrid.ts
@@ -0,0 +1,6 @@
+import { config } from "@repo/shared";
+
+export const createInitialGridColors = (): number[] => {
+  const totalCells = config.GAME_CONFIG.GRID_COLS * config.GAME_CONFIG.GRID_ROWS;
+  return new Array(totalCells).fill(-1);
+};
diff --git a/apps/server/src/domains/game/entities/map/mapPainting.ts b/apps/server/src/domains/game/entities/map/mapPainting.ts
new file mode 100644
index 0000000..c03eab1
--- /dev/null
+++ b/apps/server/src/domains/game/entities/map/mapPainting.ts
@@ -0,0 +1,22 @@
+import type { gridMapTypes } from "@repo/shared";
+
+type PaintCellParams = {
+  gridColors: number[];
+  pendingUpdates: gridMapTypes.CellUpdate[];
+  index: number;
+  teamId: number;
+};
+
+export const paintCellIfChanged = ({
+  gridColors,
+  pendingUpdates,
+  index,
+  teamId,
+}: PaintCellParams): void => {
+  if (gridColors[index] === teamId) {
+    return;
+  }
+
+  gridColors[index] = teamId;
+  pendingUpdates.push({ index, teamId });
+};
diff --git a/apps/server/src/domains/game/entities/map/mapUpdates.ts b/apps/server/src/domains/game/entities/map/mapUpdates.ts
new file mode 100644
index 0000000..091ed0b
--- /dev/null
+++ b/apps/server/src/domains/game/entities/map/mapUpdates.ts
@@ -0,0 +1,9 @@
+import type { gridMapTypes } from "@repo/shared";
+
+export const drainPendingUpdates = (
+  pendingUpdates: gridMapTypes.CellUpdate[]
+): gridMapTypes.CellUpdate[] => {
+  const updates = [...pendingUpdates];
+  pendingUpdates.length = 0;
+  return updates;
+};
diff --git a/apps/server/src/domains/game/loop/GameLoop.ts b/apps/server/src/domains/game/loop/GameLoop.ts
new file mode 100644
index 0000000..de3617c
--- /dev/null
+++ b/apps/server/src/domains/game/loop/GameLoop.ts
@@ -0,0 +1,100 @@
+import { Player } from "../entities/player/Player.js";
+import { MapStore } from "../entities/map/MapStore";
+import { getPlayerGridIndex } from "../entities/player/playerPosition.js";
+import { config } from "@repo/shared";
+import type { gridMapTypes } from "@repo/shared";
+import { logEvent } from "@server/logging/logEvent";
+
+// コールバックで渡すデータの型定義
+export interface TickData {
+  players: {
+    id: string;
+    x: number;
+    y: number;
+    teamId: number;
+  }[];
+  cellUpdates: gridMapTypes.CellUpdate[];
+}
+
+export class GameLoop {
+  private loopId: NodeJS.Timeout | null = null;
+  private startTime: number = 0;
+
+  constructor(
+    private roomId: string,
+    private tickRate: number,
+    private playerIds: string[],
+    private players: Map<string, Player>,
+    private mapStore: MapStore,
+    private onTick: (data: TickData) => void,
+    private onGameEnd: () => void   // ゲーム終了時のコールバック
+  ) {}
+
+  start() {
+    // 既にループが回っている場合は何もしない
+    if (this.loopId) return;
+
+    this.startTime = Date.now();
+
+    this.loopId = setInterval(() => {
+      // 時間経過のチェック
+      const elapsedTimeMs = Date.now() - this.startTime;
+      if (elapsedTimeMs >= config.GAME_CONFIG.GAME_DURATION_SEC * 1000) {
+        // ゲーム終了時にループを止めて終了処理へ
+        this.stop();
+        this.onGameEnd();
+        return; // 今回のフレームの座標更新はスキップ
+      }
+
+      const playersData: TickData["players"] = [];
+
+      // 1. 各プレイヤーの座標処理とマス塗りの判定
+      this.playerIds.forEach(id => {
+        const player = this.players.get(id);
+        if (!player) return;
+
+        const gridIndex = getPlayerGridIndex(player);
+        if (gridIndex !== null) {
+          this.mapStore.paintCell(gridIndex, player.teamId);
+        }
+
+        // 送信用のプレイヤーデータを構築
+        playersData.push({
+          id: player.id,
+          x: player.x,
+          y: player.y,
+          teamId: player.teamId,
+        });
+      });
+
+      // 2. マスの差分（Diff）を取得
+      const cellUpdates = this.mapStore.getAndClearUpdates();
+
+      // 3. 通信層（GameHandler）へデータを渡す
+      this.onTick({
+        players: playersData,
+        cellUpdates: cellUpdates,
+      });
+      
+    }, this.tickRate);
+
+    logEvent("GameLoop", {
+      event: "GAME_LOOP",
+      result: "started",
+      roomId: this.roomId,
+      tickRate: this.tickRate,
+    });
+  }
+
+  stop() {
+    if (this.loopId) {
+      clearInterval(this.loopId);
+      this.loopId = null;
+      logEvent("GameLoop", {
+        event: "GAME_LOOP",
+        result: "stopped",
+        roomId: this.roomId,
+      });
+    }
+  }
+}
\ No newline at end of file