diff --git a/app/api/users.py b/app/api/users.py
index 043dd98..3b51e29 100644
--- a/app/api/users.py
+++ b/app/api/users.py
@@ -1,5 +1,13 @@
-from fastapi import APIRouter, File, Form, UploadFile
+from fastapi import APIRouter, File, Form, HTTPException, UploadFile
 from app.models.user import UserResponse
+from app.services.user_service import (
+    authenticate_user,
+    delete_user,
+    get_user,
+    register_user,
+)
+
+
 
 router = APIRouter()
 
@@ -7,22 +15,45 @@
 @router.post("/users/register", response_model=UserResponse)
 async def register(user_id: str = Form(...), image: UploadFile = File(...)):
     """회원 등록 엔드포인트"""
-    pass
+    image_data = await image.read()
+    registered_user = register_user(user_id, image_data)
+
+    return UserResponse(
+        user_id=registered_user["user_id"],
+        registered_at=registered_user["registered_at"],
+    )
 
 
 @router.post("/users/authenticate")
 async def authenticate(image: UploadFile = File(...)):
     """회원 인증 엔드포인트"""
-    pass
+    image_data = await image.read()
+    user_id = authenticate_user(image_data)
+
+    if user_id is None:
+        raise HTTPException(status_code=401, detail="인증 실패: 사용자 없음")
+
+    return {"user_id": user_id}
+
 
 
 @router.get("/users/{user_id}")
 def get_user_info(user_id: str):
     """회원 정보 조회 엔드포인트"""
-    pass
+    user_info = get_user(user_id)
+
+    if user_info is None:
+        raise HTTPException(status_code=404, detail="사용자가 존재하지 않습니다.")
+
+    return user_info
 
 
 @router.delete("/users/{user_id}")
 def delete_user_info(user_id: str):
     """회원 삭제 엔드포인트"""
-    pass
+   result = delete_user(user_id)
+
+    if not result:
+        raise HTTPException(status_code=404, detail="사용자가 존재하지 않습니다.")
+
+    return {"message": "사용자가 성공적으로 삭제되었습니다."}
diff --git a/app/face/face_db.py b/app/face/face_db.py
index 380ae3a..f0b2699 100644
--- a/app/face/face_db.py
+++ b/app/face/face_db.py
@@ -1,16 +1,29 @@
+import json
+import os
+from datetime import datetime
+
 DB_PATH = "face_db.json"
 
 
 def save_user(user_id, embedding):
     """사용자 등록"""
-    pass
+    db = load_db()
+    db[user_id] = {"embedding": embedding, "registered_at": str(datetime.now())}
+    with open(DB_PATH, "w") as f:
+        json.dump(db, f)
+
 
 
 def load_db():
     """데이터베이스 로드"""
-    pass
+    if not os.path.exists(DB_PATH):
+        return {}
+    with open(DB_PATH, "r") as f:
+        return json.load(f)
+
 
 
 def save_db(db):
     """데이터베이스 저장"""
-    pass
+     with open(DB_PATH, "w") as f:
+        json.dump(db, f)
diff --git a/app/face/face_embedding.py b/app/face/face_embedding.py
index 3acfb0c..92f363d 100644
--- a/app/face/face_embedding.py
+++ b/app/face/face_embedding.py
@@ -1,8 +1,11 @@
 def extract_embedding(image):
     """이미지에서 임베딩 추출"""
-    pass
+    embedding = DeepFace.represent(img_path)[0]["embedding"]
+    return embedding
 
 
 def verify_embedding(embedding1, embedding2):
+def verify_embedding(embedding1: list, embedding2: list) -> bool:
     """두 임베딩이 같은 사람인지 검증"""
-    pass
+    is_same_person = DeepFace.verify(embedding1, embedding2)["verified"]
+    return is_same_person
diff --git a/app/services/user_service.py b/app/services/user_service.py
index 410b807..8444854 100644
--- a/app/services/user_service.py
+++ b/app/services/user_service.py
@@ -1,18 +1,54 @@
+from datetime import datetime
+
+import cv2
+import numpy as np
+
+from app.face.face_db import load_db, save_db, save_user
+from app.face.face_embedding import extract_embedding, verify_embedding
+
 def register_user(user_id: str, image_bytes: bytes) -> dict:
     """이미지와 ID로 회원 등록"""
-    pass
+    
+    image_np = np.frombuffer(image_bytes, dtype=np.uint8)
+    image = cv2.imdecode(image_np, cv2.IMREAD_COLOR)
+    embedding = extract_embedding(image)
+    save_user(user_id, embedding)
+    return {"user_id": user_id, "registered_at": str(datetime.now())}
 
 
 def authenticate_user(image_bytes: bytes):
     """이미지로 회원 인증"""
-    pass
+    image_np = np.frombuffer(image_bytes, dtype=np.uint8)
+    image = cv2.imdecode(image_np, cv2.IMREAD_COLOR)
+    db = load_db()
+
+    embedding_to_check = extract_embedding(image)
+
+    for user_id, data in db.items():
+        if verify_embedding(data["embedding"], embedding_to_check):
+            return user_id
+
+    return None  # 인증 실패
+
 
 
 def get_user(user_id):
     """user_id로 회원 정보 조회"""
-    pass
+    db = load_db()
+    user_data = db.get(user_id)
+
+    if user_data:
+        return {"user_id": user_id, "registered_at": user_data["registered_at"]}
+    else:
+        return None  # 사용자 없음
+
 
 
 def delete_user(user_id):
     """user_id로 회원 삭제"""
-    pass
+    db = load_db()
+    if user_id in db:
+        del db[user_id]
+        save_db(db)
+        return True
+    return False