diff --git a/backend/app/collector.py b/backend/app/collector.py
index 434ac39..b9ce716 100644
--- a/backend/app/collector.py
+++ b/backend/app/collector.py
@@ -1,7 +1,7 @@
 import requests
 from typing import Dict, Any
 
-from .db import get_draw, upsert_draw
+from .db import get_draw, upsert_draw, upsert_many_draws, get_latest_draw, count_draws
 
 def _normalize_item(item: dict) -> dict:
     # smok95 all.json / latest.json 구조
@@ -27,20 +27,13 @@ def sync_all_from_json(all_url: str) -> Dict[str, Any]:
     r.raise_for_status()
     data = r.json()  # list[dict]
 
-    inserted = 0
-    skipped = 0
+    # 정규화
+    rows = [_normalize_item(item) for item in data]
+    
+    # Bulk Insert (성능 향상)
+    upsert_many_draws(rows)
 
-    for item in data:
-        row = _normalize_item(item)
-
-        if get_draw(row["drw_no"]):
-            skipped += 1
-            continue
-
-        upsert_draw(row)
-        inserted += 1
-
-    return {"mode": "all_json", "url": all_url, "inserted": inserted, "skipped": skipped, "total": len(data)}
+    return {"mode": "all_json", "url": all_url, "total": len(rows)}
 
 def sync_latest(latest_url: str) -> Dict[str, Any]:
     r = requests.get(latest_url, timeout=30)
@@ -53,3 +46,40 @@ def sync_latest(latest_url: str) -> Dict[str, Any]:
 
     return {"mode": "latest_json", "url": latest_url, "was_new": (before is None), "drawNo": row["drw_no"]}
 
+def sync_ensure_all(latest_url: str, all_url: str) -> Dict[str, Any]:
+    """
+    1회부터 최신 회차까지 빠짐없이 있는지 확인하고, 없으면 전체 동기화 수행.
+    반환값: {"synced": bool, "reason": str, ...}
+    """
+    # 1. 원격 최신 회차 확인
+    try:
+        r = requests.get(latest_url, timeout=10)
+        r.raise_for_status()
+        remote_item = r.json()
+        remote_no = int(remote_item["draw_no"])
+    except Exception as e:
+        # 외부 통신 실패 시, 그냥 로컬 데이터로 진행하도록 에러 억제 (혹은 에러 발생)
+        # 여기서는 통계 기능 작동이 우선이므로 로그만 남기고 pass하고 싶지만,
+        # 확실한 동기화를 위해 에러를 던지거나 False 리턴
+        return {"synced": False, "error": str(e)}
+
+    # 2. 로컬 상태 확인
+    local_latest_row = get_latest_draw()
+    local_no = local_latest_row["drw_no"] if local_latest_row else 0
+    local_cnt = count_draws()
+
+    # 3. 동기화 필요 여부 판단
+    # - 전체 개수가 최신 회차 번호보다 적으면 중간에 빈 것 (1회부터 시작한다고 가정)
+    # - 혹은 DB 최신 번호가 원격보다 낮으면 업데이트 필요
+    need_sync = (local_no < remote_no) or (local_cnt < local_no)
+    
+    if not need_sync:
+        return {"synced": True, "updated": False, "local_no": local_no}
+
+    # 4. 전체 동기화 실행
+    # (단순 latest sync로는 중간 구멍을 못 채우므로, 구멍이 있거나 차이가 크면 all_sync 수행)
+    # 만약 차이가 1회차 뿐이고 구멍이 없다면 sync_latest만 해도 되지만, 
+    # 로직 단순화를 위해 missing 감지 시 그냥 all_sync (Bulk Insert라 빠름)
+    res = sync_all_from_json(all_url)
+    return {"synced": True, "updated": True, "detail": res}
+
diff --git a/backend/app/db.py b/backend/app/db.py
index b0b25ee..193105a 100644
--- a/backend/app/db.py
+++ b/backend/app/db.py
@@ -88,6 +88,30 @@ def upsert_draw(row: Dict[str, Any]) -> None:
             ),
         )
 
+def upsert_many_draws(rows: List[Dict[str, Any]]) -> None:
+    data = [
+        (
+            int(r["drw_no"]), str(r["drw_date"]),
+            int(r["n1"]), int(r["n2"]), int(r["n3"]),
+            int(r["n4"]), int(r["n5"]), int(r["n6"]),
+            int(r["bonus"])
+        ) for r in rows
+    ]
+    with _conn() as conn:
+        conn.executemany(
+            """
+            INSERT INTO draws (drw_no, drw_date, n1, n2, n3, n4, n5, n6, bonus)
+            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+            ON CONFLICT(drw_no) DO UPDATE SET
+              drw_date=excluded.drw_date,
+              n1=excluded.n1, n2=excluded.n2, n3=excluded.n3,
+              n4=excluded.n4, n5=excluded.n5, n6=excluded.n6,
+              bonus=excluded.bonus,
+              updated_at=datetime('now')
+            """,
+            data
+        )
+
 def get_latest_draw() -> Optional[Dict[str, Any]]:
     with _conn() as conn:
         r = conn.execute("SELECT * FROM draws ORDER BY drw_no DESC LIMIT 1").fetchone()
diff --git a/backend/app/main.py b/backend/app/main.py
index 9463059..4fb2820 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -10,7 +10,8 @@ from .db import (
     update_recommendation,
 )
 from .recommender import recommend_numbers
-from .collector import sync_latest
+from .recommender import recommend_numbers
+from .collector import sync_latest, sync_ensure_all
 
 app = FastAPI()
 scheduler = BackgroundScheduler(timezone=os.getenv("TZ", "Asia/Seoul"))
@@ -118,6 +119,10 @@ def admin_sync_latest():
 
 @app.get("/api/lotto/stats")
 def api_stats():
+    # 1. 데이터 완전성 보장 (없으면 가져옴)
+    sync_ensure_all(LATEST_URL, ALL_URL)
+    
+    # 2. 전체 데이터 조회
     draws = get_all_draw_numbers()
     if not draws:
         raise HTTPException(status_code=404, detail="No data yet")