diff --git a/src/main/java/com/postsquad/scoup/web/group/domain/Group.java b/src/main/java/com/postsquad/scoup/web/group/domain/Group.java
index 1c580e25..143969b2 100644
--- a/src/main/java/com/postsquad/scoup/web/group/domain/Group.java
+++ b/src/main/java/com/postsquad/scoup/web/group/domain/Group.java
@@ -2,21 +2,12 @@
 
 import com.postsquad.scoup.web.common.BaseEntity;
 import com.postsquad.scoup.web.group.controller.request.GroupModificationRequest;
-import com.postsquad.scoup.web.schedule.domain.ConfirmedSchedule;
 import com.postsquad.scoup.web.schedule.domain.Schedule;
-import com.postsquad.scoup.web.schedule.domain.ScheduleCandidate;
 import com.postsquad.scoup.web.user.domain.User;
 import lombok.*;
-import org.hibernate.annotations.Fetch;
-import org.hibernate.annotations.FetchMode;
-import org.hibernate.annotations.LazyCollection;
-import org.hibernate.annotations.LazyCollectionOption;
 
 import javax.persistence.*;
-import java.util.ArrayList;
-import java.util.LinkedHashSet;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 @Getter
@@ -39,6 +30,14 @@ public class Group extends BaseEntity {
     @OneToMany(mappedBy = "group", cascade = CascadeType.ALL)
     private final List<Schedule> schedules = new ArrayList<>();
 
+    @ManyToMany
+    @JoinTable(
+            name = "group_member",
+            joinColumns = @JoinColumn(name = "group_id"),
+            inverseJoinColumns = @JoinColumn(name = "user_id")
+    )
+    private final List<User> members = new ArrayList<>();
+
     protected Group(String name, String description, User owner) {
         this.name = name;
         this.description = description;
@@ -72,4 +71,9 @@ public void addSchedule(Schedule schedule) {
     public void addSchedules(List<Schedule> schedules) {
         this.schedules.addAll(schedules);
     }
+
+    public void addMember(User user) {
+        user.getJoinedGroups().add(this);
+        this.members.add(user);
+    }
 }
diff --git a/src/main/java/com/postsquad/scoup/web/user/domain/User.java b/src/main/java/com/postsquad/scoup/web/user/domain/User.java
index 6cb62876..0b8aea78 100644
--- a/src/main/java/com/postsquad/scoup/web/user/domain/User.java
+++ b/src/main/java/com/postsquad/scoup/web/user/domain/User.java
@@ -2,6 +2,7 @@
 
 import com.postsquad.scoup.web.auth.OAuthType;
 import com.postsquad.scoup.web.common.BaseEntity;
+import com.postsquad.scoup.web.group.domain.Group;
 import lombok.*;
 
 import javax.persistence.*;
@@ -36,6 +37,9 @@ public class User extends BaseEntity {
     @CollectionTable(name = "oauth_user", joinColumns = @JoinColumn(name = "user_id"))
     private List<OAuthUser> oAuthUsers = new ArrayList<>();
 
+    @ManyToMany(mappedBy = "members")
+    private List<Group> joinedGroups = new ArrayList<>();
+
     protected User(String nickname, String username, String email, String avatarUrl, String password, List<OAuthUser> oAuthUsers) {
         this.nickname = nickname;
         this.username = username;