diff --git a/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/controller/AuthController.java b/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/controller/AuthController.java
index b0e425e4..5da466f6 100644
--- a/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/controller/AuthController.java
+++ b/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/controller/AuthController.java
@@ -1,12 +1,11 @@
 package com.gltkorea.icebang.domain.auth.controller;
 
-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;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.*;
 
 import com.gltkorea.icebang.common.dto.ApiResponse;
 import com.gltkorea.icebang.domain.auth.dto.RegisterDto;
+import com.gltkorea.icebang.domain.auth.service.AuthService;
 
 import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
@@ -15,10 +14,12 @@
 @RequestMapping("/v0/auth")
 @RequiredArgsConstructor
 public class AuthController {
+  private final AuthService authService;
 
   @PostMapping("/register")
-  public ApiResponse<String> register(@Valid @RequestBody RegisterDto registerDto) {
-
-    throw new RuntimeException("Not implemented");
+  @ResponseStatus(HttpStatus.CREATED)
+  public ApiResponse<Void> register(@Valid @RequestBody RegisterDto registerDto) {
+    authService.registerUser(registerDto);
+    return ApiResponse.success(null);
   }
 }
diff --git a/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/dto/RegisterDto.java b/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/dto/RegisterDto.java
index 68feaa42..1ff305aa 100644
--- a/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/dto/RegisterDto.java
+++ b/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/dto/RegisterDto.java
@@ -17,14 +17,17 @@
 @AllArgsConstructor
 @NoArgsConstructor
 public class RegisterDto {
+  @Null private BigInteger id;
 
   @NotBlank(message = "사용자명은 필수입니다")
-  private String userName;
+  private String name;
 
   @NotBlank(message = "이메일은 필수입니다")
   @Email(message = "올바른 이메일 형식이 아닙니다")
   private String email;
 
+  @Null private BigInteger userOrgId;
+
   @NotNull(message = "조직 선택은 필수입니다")
   private BigInteger orgId;
 
@@ -38,4 +41,6 @@ public class RegisterDto {
   private Set<BigInteger> roleIds;
 
   @Null private String password;
+
+  @Null private String status;
 }
diff --git a/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/service/AuthService.java b/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/service/AuthService.java
index d5358649..18010ed5 100644
--- a/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/service/AuthService.java
+++ b/apps/user-service/src/main/java/com/gltkorea/icebang/domain/auth/service/AuthService.java
@@ -22,12 +22,24 @@ public class AuthService {
   private final EmailService emailService;
 
   public void registerUser(RegisterDto registerDto) {
+    if (authMapper.existsByEmail(registerDto.getEmail())) {
+      throw new IllegalArgumentException("이미 가입된 이메일입니다.");
+    }
     String randomPassword = passwordGenerator.generate();
     String hashedPassword = passwordEncoder.encode(randomPassword);
 
     registerDto.setPassword(hashedPassword);
+    registerDto.setStatus("PENDING");
 
-    // @TODO:: Auth mapper 호출하여 insert
+    authMapper.insertUser(registerDto);
+
+    // 2. user_organizations insert → userOrgId 반환
+    authMapper.insertUserOrganization(registerDto);
+
+    // 3. user_roles insert (foreach)
+    if (registerDto.getRoleIds() != null && !registerDto.getRoleIds().isEmpty()) {
+      authMapper.insertUserRoles(registerDto);
+    }
 
     EmailRequest emailRequest =
         EmailRequest.builder()
diff --git a/apps/user-service/src/main/java/com/gltkorea/icebang/domain/user/service/UserService.java b/apps/user-service/src/main/java/com/gltkorea/icebang/domain/user/service/UserService.java
index 10ec3000..fcf87ac9 100644
--- a/apps/user-service/src/main/java/com/gltkorea/icebang/domain/user/service/UserService.java
+++ b/apps/user-service/src/main/java/com/gltkorea/icebang/domain/user/service/UserService.java
@@ -19,7 +19,7 @@ public class UserService {
   public void registerUser(RegisterDto registerDto) {
     Users user =
         Users.builder()
-            .name(registerDto.getUserName())
+            .name(registerDto.getName())
             .email(registerDto.getEmail())
             .password(registerDto.getPassword())
             .status("PENDING")
diff --git a/apps/user-service/src/main/java/com/gltkorea/icebang/mapper/AuthMapper.java b/apps/user-service/src/main/java/com/gltkorea/icebang/mapper/AuthMapper.java
index 14851fc0..09033730 100644
--- a/apps/user-service/src/main/java/com/gltkorea/icebang/mapper/AuthMapper.java
+++ b/apps/user-service/src/main/java/com/gltkorea/icebang/mapper/AuthMapper.java
@@ -6,5 +6,11 @@
 
 @Mapper
 public interface AuthMapper {
-  void registerUser(RegisterDto registerDto);
+  boolean existsByEmail(String email);
+
+  int insertUser(RegisterDto dto); // users insert
+
+  int insertUserOrganization(RegisterDto dto); // user_organizations insert
+
+  int insertUserRoles(RegisterDto dto); // user_roles insert (foreach)
 }
diff --git a/apps/user-service/src/main/resources/mybatis/mapper/AuthMapper.xml b/apps/user-service/src/main/resources/mybatis/mapper/AuthMapper.xml
index 4ce5afbb..0c36cc21 100644
--- a/apps/user-service/src/main/resources/mybatis/mapper/AuthMapper.xml
+++ b/apps/user-service/src/main/resources/mybatis/mapper/AuthMapper.xml
@@ -3,19 +3,35 @@
         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 
 <mapper namespace="com.gltkorea.icebang.mapper.AuthMapper">
-    <insert id="registerUser" parameterType="com.gltkorea.icebang.domain.auth.dto.RegisterDto">
-        <selectKey keyProperty="id"  resultType="java.math.BigInteger"  order="AFTER">
-            SELECT LAST_INSERT_ID()
-        </selectKey>
+
+    <!-- 이메일 중복 여부 확인 -->
+    <select id="existsByEmail" parameterType="string" resultType="boolean">
+        SELECT EXISTS(
+            SELECT 1
+            FROM users
+            WHERE email = #{email}
+        )
+    </select>
+
+    <!-- 1. users INSERT & PK 반환 -->
+    <insert id="insertUser" parameterType="com.gltkorea.icebang.domain.auth.dto.RegisterDto" useGeneratedKeys="true" keyProperty="id">
         INSERT INTO users (name, email, password)
-        VALUES (#{name}, #{email}, #{password})
+        VALUES (#{name}, #{email}, #{password});
+    </insert>
 
+    <!-- 2. user_organizations INSERT -->
+    <insert id="insertUserOrganization" parameterType="com.gltkorea.icebang.domain.auth.dto.RegisterDto" useGeneratedKeys="true" keyProperty="userOrgId">
         INSERT INTO user_organizations (user_id, organization_id, department_id, position_id, status)
-        VALUES (#{id}, #{organizationId}, #{departmentId}, #{positionId}, #{status})
+        VALUES (#{id}, #{orgId}, #{deptId}, #{positionId}, #{status});
+    </insert>
 
+    <!-- 3. user_roles INSERT (foreach) -->
+    <insert id="insertUserRoles" parameterType="com.gltkorea.icebang.domain.auth.dto.RegisterDto">
         INSERT INTO user_roles (user_organization_id, role_id)
-        SELECT uo.id, #{roleId}
-        FROM user_organizations uo
-        WHERE uo.user_id = #{id}
+        VALUES
+        <foreach collection="roleIds" item="roleId" separator=",">
+            (#{userOrgId}, #{roleId})
+        </foreach>
     </insert>
-</mapper>
\ No newline at end of file
+
+</mapper>