diff --git a/.gitignore b/.gitignore
index b63da45..835efad 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,7 +3,7 @@ build/
 !gradle/wrapper/gradle-wrapper.jar
 !**/src/main/**/build/
 !**/src/test/**/build/
-
+application.yaml
 ### IntelliJ IDEA ###
 .idea/modules.xml
 .idea/jarRepositories.xml
diff --git a/src/main/java/org/sopt/diary/api/DiaryListResponse.java b/src/main/java/org/sopt/diary/api/DiaryListResponse.java
index d9684f4..e9a288a 100644
--- a/src/main/java/org/sopt/diary/api/DiaryListResponse.java
+++ b/src/main/java/org/sopt/diary/api/DiaryListResponse.java
@@ -16,4 +16,4 @@ public List<DiaryResponse> getDiaryList(){
     }
 
 
-}
+}
\ No newline at end of file
diff --git a/src/main/java/org/sopt/diary/api/SimpleDiaryResponse.java b/src/main/java/org/sopt/diary/api/SimpleDiaryResponse.java
index 090e92e..63ee202 100644
--- a/src/main/java/org/sopt/diary/api/SimpleDiaryResponse.java
+++ b/src/main/java/org/sopt/diary/api/SimpleDiaryResponse.java
@@ -16,4 +16,4 @@ public Long getDiaryId() {
     public String getMessage() {
         return content;
     }
-}
+}
\ No newline at end of file
diff --git a/src/main/java/org/sopt/diary/repository/DiaryEntity.java b/src/main/java/org/sopt/diary/repository/DiaryEntity.java
index a50b983..f0c0b16 100644
--- a/src/main/java/org/sopt/diary/repository/DiaryEntity.java
+++ b/src/main/java/org/sopt/diary/repository/DiaryEntity.java
@@ -1,6 +1,7 @@
 package org.sopt.diary.repository;
 
 import jakarta.persistence.*;
+import org.sopt.diary.user.repository.UserEntity;
 import java.time.LocalDateTime;
 
 @Entity
@@ -18,26 +19,43 @@ public class DiaryEntity {
 
     @Column
     private LocalDateTime createdAt;
+
     @Column // 카테고리 필드 추가
     private String category;
 
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "user_id", nullable = true)
+    private UserEntity user;
 
     // 기본 생성자 (JPA에서 사용)
-    public DiaryEntity() {}
+    public DiaryEntity() {
+        this.createdAt = LocalDateTime.now(); // 기본 생성 시점 설정
+    }
 
-    // 필수값인 title과 content를 받는 생성자
-    public DiaryEntity(String title, String content,String category) {
-        if (title == null || content == null ) {
+    // UserEntity가 포함된 생성자
+    public DiaryEntity(String title, String content, String category, UserEntity user) {
+        if (title == null || content == null) {
             throw new IllegalArgumentException("Title과 Content는 반드시 필요합니다.");
         }
         this.title = title;
         this.content = content;
         this.category = category;
-        this.createdAt = LocalDateTime.now(); // 생성 시점의 현재 시간
+        this.user = user;
+        this.createdAt = LocalDateTime.now();
+    }
 
+    // UserEntity 없이 사용할 수 있는 생성자 추가
+    public DiaryEntity(String title, String content, String category) {
+        if (title == null || content == null) {
+            throw new IllegalArgumentException("Title과 Content는 반드시 필요합니다.");
+        }
+        this.title = title;
+        this.content = content;
+        this.category = category;
+        this.createdAt = LocalDateTime.now();
     }
 
-    // Getter
+    // Getter 메서드들
     public Long getId() {
         return id;
     }
@@ -54,8 +72,15 @@ public LocalDateTime getCreatedAt() {
         return createdAt;
     }
 
-    
+    public String getCategory() {
+        return category;
+    }
+
+    public UserEntity getUser() {
+        return user;
+    }
 
+    // Setter 메서드들
     public void setTitle(String title) {
         this.title = title;
     }
@@ -68,11 +93,11 @@ public void setCreatedAt(LocalDateTime createdAt) {
         this.createdAt = createdAt;
     }
 
-    public String getCategory() {
-        return category;
-    }
-
     public void setCategory(String category) {
         this.category = category;
     }
+
+    public void setUser(UserEntity user) {
+        this.user = user;
+    }
 }
diff --git a/src/main/java/org/sopt/diary/service/Diary.java b/src/main/java/org/sopt/diary/service/Diary.java
index 5dc5f1e..1793d6a 100644
--- a/src/main/java/org/sopt/diary/service/Diary.java
+++ b/src/main/java/org/sopt/diary/service/Diary.java
@@ -17,4 +17,4 @@ public long getId() {
     public String getTitle() {  // name 대신 title 사용
         return title;
     }
-}
+}
\ No newline at end of file
diff --git a/src/main/java/org/sopt/diary/user/api/UserController.java b/src/main/java/org/sopt/diary/user/api/UserController.java
new file mode 100644
index 0000000..61d320a
--- /dev/null
+++ b/src/main/java/org/sopt/diary/user/api/UserController.java
@@ -0,0 +1,38 @@
+package org.sopt.diary.user.api;
+
+
+import org.sopt.diary.user.repository.UserEntity;
+import org.sopt.diary.user.service.UserService;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/users")
+public class UserController {
+
+
+    private UserService userService;
+
+    public UserController(UserService userService){
+        this.userService = userService;
+    }
+
+    //회원가입 API
+
+    @PostMapping("/signup")
+    public ResponseEntity<UserEntity> registerUser(@RequestBody UserSignupRequest signupRequest){
+        UserEntity registeredUser = userService.registerUser(signupRequest);
+        return ResponseEntity.status(HttpStatus.OK).body(registeredUser);
+    }
+
+    @PostMapping("/login")
+    public ResponseEntity<UserEntity> loginUser(@RequestBody UserLoginRequst loginRequst){
+        UserEntity user = userService.loginUser(loginRequst);
+        return ResponseEntity.status(HttpStatus.OK).body(user);
+    }
+
+}
diff --git a/src/main/java/org/sopt/diary/user/api/UserLoginRequst.java b/src/main/java/org/sopt/diary/user/api/UserLoginRequst.java
new file mode 100644
index 0000000..43dd491
--- /dev/null
+++ b/src/main/java/org/sopt/diary/user/api/UserLoginRequst.java
@@ -0,0 +1,33 @@
+package org.sopt.diary.user.api;
+
+public class UserLoginRequst {
+    private String username;
+    private String password;
+
+    //기본생성자
+    public  UserLoginRequst(){}
+
+
+    //매개변수 받는 생성자
+
+    public UserLoginRequst(String username,String password){
+        this.username = username;
+        this.password = password;
+    }
+
+    // Getter 메서드들
+    public String getUsername() {
+        return username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    // Setter 메서드들
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+
+}
diff --git a/src/main/java/org/sopt/diary/user/api/UserResponse.java b/src/main/java/org/sopt/diary/user/api/UserResponse.java
new file mode 100644
index 0000000..292870a
--- /dev/null
+++ b/src/main/java/org/sopt/diary/user/api/UserResponse.java
@@ -0,0 +1,40 @@
+package org.sopt.diary.user.api;
+
+public class UserResponse {
+    private  Long id;
+    private String username;
+    private  String nickname;
+
+
+    public UserResponse(){}
+
+    // 매개변수를 받는 생성자
+    public UserResponse(Long id, String username, String nickname) {
+        this.id = id;
+        this.username = username;
+        this.nickname = nickname;
+    }
+
+    // Getter 메서드들
+    public Long getId() {
+        return id;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public String getNickname() {
+        return nickname;
+    }
+
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public void setNickname(String nickname) {
+        this.nickname = nickname;
+    }
+
+}
diff --git a/src/main/java/org/sopt/diary/user/api/UserSignupRequest.java b/src/main/java/org/sopt/diary/user/api/UserSignupRequest.java
new file mode 100644
index 0000000..db94b3a
--- /dev/null
+++ b/src/main/java/org/sopt/diary/user/api/UserSignupRequest.java
@@ -0,0 +1,40 @@
+package org.sopt.diary.user.api;
+
+public class UserSignupRequest {
+    private String username;
+    private String password;
+    private String nickname;
+
+    // 기본 생성자
+    public UserSignupRequest() {}
+
+    // 매개변수를 받는 생성자
+    public UserSignupRequest(String username, String password, String nickname) {
+        this.username = username;
+        this.password = password;
+        this.nickname = nickname;
+    }
+
+    // Getter 메서드들
+    public String getUsername() {
+        return username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public String getNickname() {
+        return nickname;
+    }
+
+    // Setter 메서드들
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+
+    public void setNickname(String nickname) {
+        this.nickname = nickname;
+    }
+}
diff --git a/src/main/java/org/sopt/diary/user/repository/UserEntity.java b/src/main/java/org/sopt/diary/user/repository/UserEntity.java
new file mode 100644
index 0000000..f10249e
--- /dev/null
+++ b/src/main/java/org/sopt/diary/user/repository/UserEntity.java
@@ -0,0 +1,58 @@
+package org.sopt.diary.user.repository;
+
+import jakarta.persistence.*;
+import org.sopt.diary.repository.DiaryEntity;
+import java.util.List;
+
+@Entity
+@Table(name="user_table")
+public class UserEntity {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(name = "username", nullable = false, unique = true)
+    private String username;
+
+    @Column(name = "password", nullable = false)
+    private String password;
+
+    @Column(name = "nickname", nullable = false)
+    private String nickname;
+
+    @OneToMany(mappedBy = "user")
+    private List<DiaryEntity> diaries;
+
+    // 기본 생성자
+    public UserEntity() {
+    }
+    // 모든 필드를 받는 생성자 추가
+    public UserEntity(String username, String password, String nickname) {
+        this.username = username;
+        this.password = password;
+        this.nickname = nickname;
+    }
+    // Getter 메서드들
+    public Long getId() {
+        return id;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public String getNickname() {
+        return nickname;
+    }
+
+    public List<DiaryEntity> getDiaries() {
+        return diaries;
+    }
+}
+
+
diff --git a/src/main/java/org/sopt/diary/user/repository/UserRepository.java b/src/main/java/org/sopt/diary/user/repository/UserRepository.java
new file mode 100644
index 0000000..db3e120
--- /dev/null
+++ b/src/main/java/org/sopt/diary/user/repository/UserRepository.java
@@ -0,0 +1,11 @@
+package org.sopt.diary.user.repository;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+public interface UserRepository extends JpaRepository <UserEntity,Long> {
+    Optional<UserEntity> findByUsername(String name);
+
+    boolean existsByNickname(String nickname);
+}
diff --git a/src/main/java/org/sopt/diary/user/service/User.java b/src/main/java/org/sopt/diary/user/service/User.java
new file mode 100644
index 0000000..95b6416
--- /dev/null
+++ b/src/main/java/org/sopt/diary/user/service/User.java
@@ -0,0 +1,4 @@
+package org.sopt.diary.user.service;
+
+public class User {
+}
diff --git a/src/main/java/org/sopt/diary/user/service/UserService.java b/src/main/java/org/sopt/diary/user/service/UserService.java
new file mode 100644
index 0000000..6d77ada
--- /dev/null
+++ b/src/main/java/org/sopt/diary/user/service/UserService.java
@@ -0,0 +1,54 @@
+package org.sopt.diary.user.service;
+
+
+import org.sopt.diary.user.api.UserLoginRequst;
+import org.sopt.diary.user.api.UserSignupRequest;
+import org.sopt.diary.user.repository.UserEntity;
+import org.sopt.diary.user.repository.UserRepository;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+public class UserService {
+    private final UserRepository userRepository;
+    public UserService(UserRepository userRepository) {
+        this.userRepository = userRepository;
+    }
+
+
+
+    @Transactional
+    public UserEntity registerUser(UserSignupRequest signupRequest){ //회원가입
+        checkDuplicateNickname(signupRequest.getNickname());
+        UserEntity newUser = new UserEntity(
+                signupRequest.getUsername(),signupRequest.getPassword(),signupRequest.getNickname()
+        );
+        return userRepository.save(newUser);
+    }
+
+    public UserEntity loginUser(UserLoginRequst userLoginRequest){
+        // 사용자 조회
+        return validateUserCredentials(userLoginRequest.getUsername(), userLoginRequest.getPassword());
+
+    }
+
+
+
+    //회원 가입 시,  nickname의 중복성을 체크하는 매서드
+    public void checkDuplicateNickname(String nickname){
+        if (userRepository.existsByNickname(nickname)) {
+            throw new IllegalArgumentException("닉네임이 이미 존재합니다");
+        }
+    }
+
+    //로그인 검증 매서드
+    private UserEntity validateUserCredentials(String username,String password){
+        // 사용자 조회
+        UserEntity user = userRepository.findByUsername(username)
+                .orElseThrow(() -> new IllegalArgumentException("유저가 존재하지 않습니다."));
+        if(!user.getPassword().equals(password)){
+            throw  new IllegalArgumentException("비밀번호가 틀렸어요");
+        }
+        return user;
+    }
+}
diff --git a/src/test/resources/application.yml b/src/test/resources/application.yml
new file mode 100644
index 0000000..d3d10d3
--- /dev/null
+++ b/src/test/resources/application.yml
@@ -0,0 +1,14 @@
+spring:
+  datasource:
+    driver-class-name: com.mysql.cj.jdbc.Driver
+    url: jdbc:mysql://db-2vfrih-kr.vpc-pub-cdb.ntruss.com:3306/team4
+    username: sopt-35-team4
+    password: 1q2w3e4r12!@
+  jpa:
+    show-sql: true
+    hibernate:
+      ddl-auto: none
+      dialect: org.hibernate.dialect.MySQL8Dialect
+    properties:
+      format_sql: true
+      show_sql: true
\ No newline at end of file