diff --git a/popcorn/Assets/MyGame/Scenes/MiniGame/Scripts/StageManager.cs b/popcorn/Assets/MyGame/Scenes/MiniGame/Scripts/StageManager.cs
index 62f8ae3d..6b604e50 100644
--- a/popcorn/Assets/MyGame/Scenes/MiniGame/Scripts/StageManager.cs
+++ b/popcorn/Assets/MyGame/Scenes/MiniGame/Scripts/StageManager.cs
@@ -6,54 +6,114 @@ namespace MyGame.Scenes.MiniGame.Scripts
 {
     public class StageManager : MonoBehaviour
     {
-        [SerializeField] private BackGround[] backGrounds;
         [SerializeField] private Transform stageTarget;
+        [SerializeField] private float normalTime;
+        [SerializeField] private float hardTime;
+        [SerializeField] private float extraTime;
+        [SerializeField] private float stageGenerateDistance;
+        [SerializeField] private int generateStageCount;
+        [SerializeField] private float beginStageOffset;
+        [SerializeField] private float partsToPartsOffset;
+        private Transform[] stagePrefabs;
         private Transform[] stages;
+        private float stageEndXPos;
+        private float cacheTargetXPos;
         public IObservable<float> OnFence => fenceSubject;
         private readonly Subject<float> fenceSubject = new();
+        public IReadOnlyReactiveProperty<ScrollGameDifficulty> Difficulty => difficulty;
+        private readonly ReactiveProperty<ScrollGameDifficulty> difficulty = new();
+        private IDisposable timerDisposable; 
 
         private void Start()
         {
             fenceSubject.AddTo(this);
+            difficulty.AddTo(this);
         }
 
         public void SetBeginStages(Transform[] newStages)
         {
+            difficulty.SetValueAndForceNotify(ScrollGameDifficulty.Easy);
+            stagePrefabs = newStages;
             stageTarget.DestroyAllChildrens();
-            stages = new Transform[newStages.Length];
-            var selectIndex = UnityEngine.Random.Range(0, stages.Length);
-            for (var i = 0; i < newStages.Length; i++)
+            stageEndXPos = stageTarget.position.x + beginStageOffset;
+            cacheTargetXPos = stageEndXPos;
+            GenerateStage();
+        }
+
+        private void GenerateStage()
+        {
+            var selectIndex = UnityEngine.Random.Range(0, stagePrefabs.Length);
+            for (var i = 0; i < generateStageCount; i++)
             {
-                stages[i] = Instantiate(newStages[i], stageTarget.position, Quaternion.identity, stageTarget);
-                stages[i].gameObject.SetActive(i == selectIndex);
-            }
-            stages[0].FindAllChildrensComponent<StageItem>(x =>
-            {
-                if (x.ItemType != StageItem.Type.Hole)
+                var stage = Instantiate(stagePrefabs[selectIndex], stageTarget.position + Vector3.left * 100f, Quaternion.identity, stageTarget);
+                var minPos = float.MaxValue;
+                var maxPos = float.MinValue;
+                var holePos = float.MinValue;
+                stage.FindAllChildrensComponent<StageItem>(x =>
                 {
-                    return;
+                    var xPos = x.transform.position.x;
+                    minPos = Mathf.Min(minPos, xPos);
+                    maxPos = Mathf.Max(maxPos, xPos);
+                    // 落とし穴があった場合通知
+                    if (x.ItemType != StageItem.Type.Hole)
+                    {
+                        return;
+                    }
+                    holePos = xPos;
+                });
+                var xPos = stage.position.x;
+                var minDiff = minPos - xPos;
+                var maxDiff = maxPos - xPos;
+                stage.SetPositionX(stageEndXPos - minDiff);
+                // endPos更新
+                stageEndXPos = stage.position.x + maxDiff + partsToPartsOffset;
+                // ステージの破棄
+                Observable.Interval(TimeSpan.FromSeconds(.5f))
+                    .Where(_ => stageEndXPos < cacheTargetXPos)
+                    .Subscribe(_ =>
+                    {
+                        Destroy(stage.gameObject);
+                    }).AddTo(this);
+                if (holePos > float.MinValue)
+                {
+                    Observable.NextFrame().Subscribe(_ => fenceSubject.OnNext(stage.position.x + holePos - xPos)).AddTo(this);
                 }
-
-                Observable.NextFrame().Subscribe(_ => fenceSubject.OnNext(x.transform.position.x)).AddTo(this);
-            });
-        }
-
-        public void SetSky(ScrollGameDifficulty difficulty)
-        {
-            foreach (var backGround in backGrounds)
-            {
-                backGround.SetSky(difficulty);
             }
         }
 
-        public void GenerateStage()
-        {
-            
-        }
-
         public void UpdatePos(float targetXPos)
         {
-            
+            cacheTargetXPos = targetXPos;
+            if (stageEndXPos - targetXPos <= stageGenerateDistance)
+            {
+                GenerateStage();
+            }
+        }
+
+        public void StartTimer()
+        {
+            StopTimer();
+            timerDisposable = Observable.Timer(TimeSpan.Zero, TimeSpan.FromSeconds(1))
+                .Subscribe(x =>
+                {
+                    if (x >= extraTime)
+                    {
+                        difficulty.Value = ScrollGameDifficulty.Extra;
+                    }
+                    else if (x >= hardTime)
+                    {
+                        difficulty.Value = ScrollGameDifficulty.Hard;
+                    } 
+                    else if (x >= normalTime)
+                    {
+                        difficulty.Value = ScrollGameDifficulty.Normal;
+                    }
+                }).AddTo(this);
+        }
+
+        public void StopTimer()
+        {
+            timerDisposable?.Dispose();
         }
     }
 }
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