diff --git a/src/main/java/umc7th/bulk/group/entity/Group.java b/src/main/java/umc7th/bulk/group/entity/Group.java
index d93573e..d83e19b 100644
--- a/src/main/java/umc7th/bulk/group/entity/Group.java
+++ b/src/main/java/umc7th/bulk/group/entity/Group.java
@@ -3,8 +3,10 @@
 import jakarta.persistence.*;
 import lombok.*;
 import umc7th.bulk.global.BaseTimeEntity;
+import umc7th.bulk.user.domain.User;
 
 import java.time.LocalDateTime;
+import java.util.List;
 
 @Entity
 @Getter
@@ -28,6 +30,21 @@ public class Group extends BaseTimeEntity {
 
     private LocalDateTime endDate;
 
+    @OneToMany(mappedBy = "group", fetch = FetchType.LAZY)
+    private List<User> members;
+
+    public boolean isFull() {
+        return members != null & members.size() >= 10;
+    }
+
+    public void addMember(User user) {
+        if (isFull()) {
+            throw new RuntimeException("그룹이 이미 가득 찼습니다.");
+        }
+        members.add(user);
+        user.setGroup(this);
+    }
+
     public Group(String groupName, int currentStage, LocalDateTime endDate) {
         this.groupName = groupName;
         this.currentStage = currentStage;
diff --git a/src/main/java/umc7th/bulk/group/repository/GroupRepository.java b/src/main/java/umc7th/bulk/group/repository/GroupRepository.java
index 80517fa..6e5bd7d 100644
--- a/src/main/java/umc7th/bulk/group/repository/GroupRepository.java
+++ b/src/main/java/umc7th/bulk/group/repository/GroupRepository.java
@@ -1,7 +1,14 @@
 package umc7th.bulk.group.repository;
 
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 import umc7th.bulk.group.entity.Group;
 
+import java.util.Optional;
+
 public interface GroupRepository extends JpaRepository<Group, Long> {
+
+    // 그룹 인원 수가 10 이하인 그룹 찾는 메서드, 없으면 새로 생성
+    @Query("SELECT g FROM Group g WHERE SIZE(g.members) < 10 ORDER BY g.groupId ASC")
+    Optional<Group> findGroupWithSpace();
 }
diff --git a/src/main/java/umc7th/bulk/user/config/KakaoOAuth2Config.java b/src/main/java/umc7th/bulk/user/config/KakaoOAuth2Config.java
index eaafd35..8a86488 100644
--- a/src/main/java/umc7th/bulk/user/config/KakaoOAuth2Config.java
+++ b/src/main/java/umc7th/bulk/user/config/KakaoOAuth2Config.java
@@ -13,9 +13,9 @@
 //@ConfigurationProperties(prefix = "spring.security.oauth2.client.registration.kakao")
 public class KakaoOAuth2Config {
 
-    private String clientId = "9555ae675b3e27488bd10e7f09ea12bd";
+    private String clientId;
 
-    private String clientSecret = "V1LPr6eQPAHRTKIcmeXczG63dkdlaUrF";
+    private String clientSecret;
 
-    private String redirectUri = "https://bulkapp.site/home";
+    private String redirectUri;
 }
diff --git a/src/main/java/umc7th/bulk/user/domain/User.java b/src/main/java/umc7th/bulk/user/domain/User.java
index 04d4250..cf5cbdb 100644
--- a/src/main/java/umc7th/bulk/user/domain/User.java
+++ b/src/main/java/umc7th/bulk/user/domain/User.java
@@ -157,4 +157,14 @@ public void updateGoalNutrition(MealPlanRequestDTO.TargetNutritionDTO targetNutr
         this.BMR = targetNutritionDTO.getBmr();
         this.TDEE = targetNutritionDTO.getTdee();
     }
+
+    public void setGroup(Group group) {
+        if (this.group != null) {
+            this.group.getMembers().remove(this);
+        }
+        this.group = group;
+        if (!group.getMembers().contains(this)) {
+            group.getMembers().add(this);
+        }
+    }
 }
diff --git a/src/main/java/umc7th/bulk/user/service/UserService.java b/src/main/java/umc7th/bulk/user/service/UserService.java
index bcdbdec..1aa0cf5 100644
--- a/src/main/java/umc7th/bulk/user/service/UserService.java
+++ b/src/main/java/umc7th/bulk/user/service/UserService.java
@@ -15,6 +15,8 @@
 import umc7th.bulk.character.repository.BulkCharacterRepository;
 import umc7th.bulk.global.error.GeneralErrorCode;
 import umc7th.bulk.global.error.exception.CustomException;
+import umc7th.bulk.group.entity.Group;
+import umc7th.bulk.group.repository.GroupRepository;
 import umc7th.bulk.user.annotation.CurrentUser;
 import umc7th.bulk.user.domain.User;
 import umc7th.bulk.user.exception.UserErrorCode;
@@ -22,6 +24,8 @@
 import umc7th.bulk.user.principal.PrincipalDetails;
 import umc7th.bulk.user.repository.UserRepository;
 
+import java.time.LocalDateTime;
+
 import static umc7th.bulk.user.dto.UserDTO.*;
 
 @Service
@@ -32,6 +36,7 @@ public class UserService {
     private final WebClient webClient;
     private final OAuth2AuthorizedClientService authorizedClientService;
     private final BulkCharacterRepository bulkCharacterRepository;
+    private final GroupRepository groupRepository;
 
     private static final String UNLINK_URL = "https://kapi.kakao.com/v1/user/unlink";
 
@@ -54,6 +59,16 @@ public User saveUser(String kakaoId, String email, String gender, String birthye
                 .build();
         bulkCharacterRepository.save(bulkCharacter);
 
+        // 기존 그룹 중 10명 미만인 그룹 찾기 (없으면 새 그룹 생성)
+        Group group = groupRepository.findGroupWithSpace().orElseGet(() -> {
+            Group newGroup = Group.builder()
+                    .groupName("Group_" + System.currentTimeMillis()) // 유니크한 그룹 이름 생성
+                    .currentStage(1)
+                    .endDate(LocalDateTime.now().plusDays(7)) // 그룹 종료일 7일 후 설정
+                    .build();
+            return groupRepository.save(newGroup);
+        });
+
         User user = User.builder()
                 .kakaoId(kakaoId)
                 .email(email)
@@ -67,8 +82,11 @@ public User saveUser(String kakaoId, String email, String gender, String birthye
                 .curCarbos(0L)
                 .curProteins(0L)
                 .curFats(0L)
+                .group(group)
                 .build();
 
+        group.addMember(user);
+
         return userRepository.save(user);
     }
 
diff --git a/src/main/java/umc7th/bulk/user/service/command/UserCommandServiceImpl.java b/src/main/java/umc7th/bulk/user/service/command/UserCommandServiceImpl.java
index fb7c441..b86360d 100644
--- a/src/main/java/umc7th/bulk/user/service/command/UserCommandServiceImpl.java
+++ b/src/main/java/umc7th/bulk/user/service/command/UserCommandServiceImpl.java
@@ -7,6 +7,8 @@
 import umc7th.bulk.character.entity.BulkCharacter;
 import umc7th.bulk.character.repository.BulkCharacterRepository;
 import umc7th.bulk.global.jwt.util.JwtProvider;
+import umc7th.bulk.group.entity.Group;
+import umc7th.bulk.group.repository.GroupRepository;
 import umc7th.bulk.user.domain.User;
 import umc7th.bulk.user.dto.UserRequestDTO;
 import umc7th.bulk.user.dto.UserResponseDTO;
@@ -15,6 +17,8 @@
 import umc7th.bulk.user.exception.UserException;
 import umc7th.bulk.user.repository.UserRepository;
 
+import java.time.LocalDateTime;
+
 
 @Slf4j
 @Service
@@ -25,6 +29,7 @@ public class UserCommandServiceImpl implements UserCommandService {
     private final PasswordEncoder encoder;
     private final JwtProvider jwtProvider;
     private final BulkCharacterRepository bulkCharacterRepository;
+    private final GroupRepository groupRepository;
 
     @Override
     public UserResponseDTO.UserTokenDTO signup(UserRequestDTO.SignupDTO dto) {
@@ -57,6 +62,18 @@ public UserResponseDTO.UserTokenDTO signup(UserRequestDTO.SignupDTO dto) {
                 .build();
         bulkCharacterRepository.save(bulkCharacter);
 
+        // 기존 그룹 중 10명 미만인 그룹 찾기 (없으면 새 그룹 생성)
+        Group group = groupRepository.findGroupWithSpace().orElseGet(() -> {
+            Group newGroup = Group.builder()
+                    .groupName("Group_" + System.currentTimeMillis()) // 유니크한 그룹 이름 생성
+                    .currentStage(1)
+                    .endDate(LocalDateTime.now().plusDays(7)) // 그룹 종료일 7일 후 설정
+                    .build();
+            return groupRepository.save(newGroup);
+        });
+
+
+
         // User 저장 (BulkCharacter 포함)
         User user = User.builder()
                 .email(emailKey)
@@ -64,6 +81,8 @@ public UserResponseDTO.UserTokenDTO signup(UserRequestDTO.SignupDTO dto) {
                 .accessToken(accessToken)
                 .refreshToken(refreshToken)
                 .bulkCharacter(bulkCharacter) // 🔥 BulkCharacter 설정
+                .recordComplete(false)
+                .group(group)
                 .build();
 
         try {