diff --git a/BE/src/main/java/com/codesquad/issuetracker/ragdoll/domain/Assignee.java b/BE/src/main/java/com/codesquad/issuetracker/ragdoll/domain/Assignee.java
index 44e95c3..c5d6b56 100644
--- a/BE/src/main/java/com/codesquad/issuetracker/ragdoll/domain/Assignee.java
+++ b/BE/src/main/java/com/codesquad/issuetracker/ragdoll/domain/Assignee.java
@@ -20,9 +20,7 @@ public static Assignee create(Integer id, Long issueId, Long userId) {
         return new Assignee(id, issueId, userId);
     }
 
-    public Integer getId() {
-        return id;
-    }
+    public Integer getId() { return id; }
 
     public void setId(Integer id) {
         this.id = id;
diff --git a/BE/src/main/java/com/codesquad/issuetracker/ragdoll/domain/Comment.java b/BE/src/main/java/com/codesquad/issuetracker/ragdoll/domain/Comment.java
index 58fd2b9..86a441e 100644
--- a/BE/src/main/java/com/codesquad/issuetracker/ragdoll/domain/Comment.java
+++ b/BE/src/main/java/com/codesquad/issuetracker/ragdoll/domain/Comment.java
@@ -92,7 +92,7 @@ public Builder createdDateTime(LocalDateTime createdDateTime) {
             return this;
         }
 
-        public Builder issuId(Long issueId) {
+        public Builder issueId(Long issueId) {
             this.issueId = issueId;
             return this;
         }
diff --git a/BE/src/main/java/com/codesquad/issuetracker/ragdoll/dto/milestoneVO/MilestoneInformation.java b/BE/src/main/java/com/codesquad/issuetracker/ragdoll/dto/milestoneVO/MilestoneInformation.java
index a630447..5d6fa90 100644
--- a/BE/src/main/java/com/codesquad/issuetracker/ragdoll/dto/milestoneVO/MilestoneInformation.java
+++ b/BE/src/main/java/com/codesquad/issuetracker/ragdoll/dto/milestoneVO/MilestoneInformation.java
@@ -1,19 +1,20 @@
 package com.codesquad.issuetracker.ragdoll.dto.milestoneVO;
 
 import java.util.List;
+import java.util.Set;
 
 public class MilestoneInformation {
 
     private int countOfMilestone;
 
-    private List<MilestoneSummary> milestones;
+    private Set<MilestoneSummary> milestones;
 
-    private MilestoneInformation(int countOfMilestone, List<MilestoneSummary> milestones) {
+    private MilestoneInformation(int countOfMilestone, Set<MilestoneSummary> milestones) {
         this.countOfMilestone = countOfMilestone;
         this.milestones = milestones;
     }
 
-    public MilestoneInformation create(int countOfMilestone, List<MilestoneSummary> milestones) {
+    public static MilestoneInformation create(int countOfMilestone, Set<MilestoneSummary> milestones) {
         return new MilestoneInformation(countOfMilestone, milestones);
     }
 
@@ -25,11 +26,11 @@ public void setCountOfMilestone(int countOfMilestone) {
         this.countOfMilestone = countOfMilestone;
     }
 
-    public List<MilestoneSummary> getMilestones() {
+    public Set<MilestoneSummary> getMilestones() {
         return milestones;
     }
 
-    public void setMilestones(List<MilestoneSummary> milestones) {
+    public void setMilestones(Set<MilestoneSummary> milestones) {
         this.milestones = milestones;
     }
 }