diff --git a/apps/server/src/domains/game/application/services/GamePlayerOperationService.ts b/apps/server/src/domains/game/application/services/GamePlayerOperationService.ts
index a5437d3..c528d50 100644
--- a/apps/server/src/domains/game/application/services/GamePlayerOperationService.ts
+++ b/apps/server/src/domains/game/application/services/GamePlayerOperationService.ts
@@ -53,7 +53,7 @@
     const removed = session.removePlayer(id);
     this.removePlayerFromIndexes(roomId, id, roomPlayerSet);
 
-    if (removed && session.isEmpty()) {
+    if (removed && session.getPlayers().length === 0) {
       session.dispose();
       this.sessions.delete(roomId);
       this.roomToPlayers.delete(roomId);
diff --git a/apps/server/src/domains/game/application/services/TeamAssignmentService.ts b/apps/server/src/domains/game/application/services/TeamAssignmentService.ts
index 8108586..4ee8c50 100644
--- a/apps/server/src/domains/game/application/services/TeamAssignmentService.ts
+++ b/apps/server/src/domains/game/application/services/TeamAssignmentService.ts
@@ -10,7 +10,10 @@
    * 現在のプレイヤー状況から、最も人数が少ないチームIDを算出する
    */
   public static getBalancedTeamId(currentPlayers: Map<string, Player>): number {
-    const teamCount = config.GAME_CONFIG.TEAM_COLORS.length;
+    const teamCount = config.GAME_CONFIG.TEAM_COUNT;
+    if (config.GAME_CONFIG.TEAM_COLORS.length !== teamCount) {
+      throw new Error("GAME_CONFIG mismatch: TEAM_COLORS length must equal TEAM_COUNT");
+    }
     const teamPopulations = new Array(teamCount).fill(0);
 
     // 現在の各チームの所属人数を数え上げる
diff --git a/apps/server/src/domains/game/entities/player/playerSpawn.ts b/apps/server/src/domains/game/entities/player/playerSpawn.ts
index f368069..4afc597 100644
--- a/apps/server/src/domains/game/entities/player/playerSpawn.ts
+++ b/apps/server/src/domains/game/entities/player/playerSpawn.ts
@@ -10,12 +10,12 @@
 export const createSpawnedPlayer = (id: string, teamId: number): Player => {
   const player = new Player(id, teamId); // ここにteamIdを渡す！
 
-  const { GRID_COLS, GRID_ROWS } = config.GAME_CONFIG;
+  const { GRID_COLS, GRID_ROWS, TEAM_COUNT } = config.GAME_CONFIG;
 
   let baseX = GRID_COLS / 2;
   let baseY = GRID_ROWS / 2;
 
-  switch (player.teamId % 4) {
+  switch (player.teamId % TEAM_COUNT) {
     case 0: // 左上
       baseX = 2;
       baseY = 2;
diff --git a/packages/shared/src/config/gameConfig.ts b/packages/shared/src/config/gameConfig.ts
index b73e6ca..b072e01 100644
--- a/packages/shared/src/config/gameConfig.ts
+++ b/packages/shared/src/config/gameConfig.ts
@@ -46,6 +46,7 @@
   BOMB_COOLDOWN_MS: 1200,  // 設置後に次の爆弾を置けるまでの待機時間（ms）
 
   // チームカラー設定
+  TEAM_COUNT: 4,
   // teamId インデックス順カラー配列
   TEAM_COLORS: ['#FF4B4B', '#4B4BFF', '#4BFF4B', '#FFD700'],