diff --git a/.gitignore b/.gitignore
deleted file mode 100644
index c2065bc..0000000
--- a/.gitignore
+++ /dev/null
@@ -1,37 +0,0 @@
-HELP.md
-.gradle
-build/
-!gradle/wrapper/gradle-wrapper.jar
-!**/src/main/**/build/
-!**/src/test/**/build/
-
-### STS ###
-.apt_generated
-.classpath
-.factorypath
-.project
-.settings
-.springBeans
-.sts4-cache
-bin/
-!**/src/main/**/bin/
-!**/src/test/**/bin/
-
-### IntelliJ IDEA ###
-.idea
-*.iws
-*.iml
-*.ipr
-out/
-!**/src/main/**/out/
-!**/src/test/**/out/
-
-### NetBeans ###
-/nbproject/private/
-/nbbuild/
-/dist/
-/nbdist/
-/.nb-gradle/
-
-### VS Code ###
-.vscode/
diff --git a/src/main/java/com/example/springhw31/controller/UserController.java b/src/main/java/com/example/springhw31/controller/UserController.java
index 7eca68b..1b148f7 100644
--- a/src/main/java/com/example/springhw31/controller/UserController.java
+++ b/src/main/java/com/example/springhw31/controller/UserController.java
@@ -1,16 +1,23 @@
 package com.example.springhw31.controller;
 
 import com.example.springhw31.dto.UserDto;
+import com.example.springhw31.service.UserService;
+import lombok.RequiredArgsConstructor;
 import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
 
-/**
- * 회원가입 메서드처럼 UserDto를 파라미터로 받아주세요
- */
-
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/users")
 public class UserController {
 
+  private final UserService userService;
 
+  @PostMapping
   public UserDto join(@ModelAttribute UserDto userDto) {
-
+    return userService.join(userDto);
   }
-}
+
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/springhw31/dto/UserDto.java b/src/main/java/com/example/springhw31/dto/UserDto.java
index 0cb0926..c4142ad 100644
--- a/src/main/java/com/example/springhw31/dto/UserDto.java
+++ b/src/main/java/com/example/springhw31/dto/UserDto.java
@@ -1,13 +1,13 @@
 package com.example.springhw31.dto;
 
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 import lombok.Setter;
 
-/**
- * UserDto 클래스는 수정 X
- */
+
 @Getter
 @Setter
+@NoArgsConstructor
 public class UserDto {
 
   private String username;
diff --git a/src/main/java/com/example/springhw31/entity/User.java b/src/main/java/com/example/springhw31/entity/User.java
index 4e957cc..a4cd926 100644
--- a/src/main/java/com/example/springhw31/entity/User.java
+++ b/src/main/java/com/example/springhw31/entity/User.java
@@ -1,14 +1,26 @@
 package com.example.springhw31.entity;
 
 
-/**
- * TODO: 완성된 코드 아닙니다~
- */
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.Setter;
+
+@Entity
+@Getter
+@Setter
 public class User {
 
+  @Id
+  @GeneratedValue(strategy = GenerationType.AUTO)
+  private Long id;
+
+  @Column(nullable = false, unique = true)
   private String username;
 
+  @Column(nullable = false)
   private String password;
 
+  @Column(nullable = false, unique = true)
   private String nickname;
-}
+
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/springhw31/repository/UserRepository.java b/src/main/java/com/example/springhw31/repository/UserRepository.java
index 53778ec..dcdb340 100644
--- a/src/main/java/com/example/springhw31/repository/UserRepository.java
+++ b/src/main/java/com/example/springhw31/repository/UserRepository.java
@@ -1,5 +1,14 @@
 package com.example.springhw31.repository;
 
-public class UserRepository {
+import com.example.springhw31.entity.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface UserRepository extends JpaRepository<User, Long> {
+
+    boolean existsByUsername(String username);
+
+    boolean existsByNickname(String nickname);
 
 }
diff --git a/src/main/java/com/example/springhw31/service/UserService.java b/src/main/java/com/example/springhw31/service/UserService.java
index c3e8928..8391eeb 100644
--- a/src/main/java/com/example/springhw31/service/UserService.java
+++ b/src/main/java/com/example/springhw31/service/UserService.java
@@ -1,14 +1,45 @@
 package com.example.springhw31.service;
 
 import com.example.springhw31.dto.UserDto;
+import com.example.springhw31.entity.User;
+import com.example.springhw31.repository.UserRepository;
+import jakarta.transaction.Transactional;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
 
-/**
- * Controller에 반환할 때도 DTO 객체를 반환합니다.
- */
+@Service
+@RequiredArgsConstructor
 public class UserService {
 
+  private final UserRepository userRepository;
+
+  @Transactional
   public UserDto join(UserDto userDto) {
 
+    if (userDto.getUsername() == null || userDto.getUsername().isEmpty()) {
+      throw new RuntimeException("아이디를 입력해 주세요.");
+    }
+    if (userDto.getPassword() == null || userDto.getPassword().isEmpty()) {
+      throw new RuntimeException("비밀번호를 입력해 주세요.");
+    }
+    if (userDto.getNickname() == null || userDto.getNickname().isEmpty()) {
+      throw new RuntimeException("닉네임을 입력해 주세요.");
+    }
+
+    if (userRepository.existsByUsername(userDto.getUsername())) {
+      throw new RuntimeException("아이디가 이미 존재합니다.");
+    }
+    if (userRepository.existsByNickname(userDto.getNickname())) {
+      throw new RuntimeException("닉네임이 이미 존재합니다.");
+    }
+
+    User user = new User();
+    user.setUsername(userDto.getUsername());
+    user.setPassword(userDto.getPassword());
+    user.setNickname(userDto.getNickname());
+
+    userRepository.save(user);
+    return userDto;
   }
 
 }
diff --git a/src/main/resources/application.yml b/src/main/resources/application.yml
deleted file mode 100644
index 9b78d0c..0000000
--- a/src/main/resources/application.yml
+++ /dev/null
@@ -1,15 +0,0 @@
-spring:
-  datasource:
-    url: jdbc:mysql://localhost:3306/your_database_name?useSSL=false&serverTimezone=UTC&characterEncoding=UTF-8
-    username: your_username
-    password: your_password
-    driver-class-name: com.mysql.cj.jdbc.Driver
-
-  jpa:
-    hibernate:
-      ddl-auto: create
-    show-sql: true
-    properties:
-      hibernate:
-        format_sql: true
-        dialect: org.hibernate.dialect.MySQL8Dialect
\ No newline at end of file