diff --git a/src/main/java/org/ntlab/acanthus_server/entities/Position.java b/src/main/java/org/ntlab/acanthus_server/entities/Position.java
index 89b9b71..3097f20 100644
--- a/src/main/java/org/ntlab/acanthus_server/entities/Position.java
+++ b/src/main/java/org/ntlab/acanthus_server/entities/Position.java
@@ -6,7 +6,7 @@
 import java.util.HashMap;
 import java.util.UUID;
 
-public class Position {
+public class Position implements Comparable {
     private int i;
     private float x;
     private float y;
@@ -27,4 +27,15 @@
         this.y = y;
     }
 
+    @Override
+    public int compareTo(Object o) {
+        if (o instanceof Position) {
+            if (i < ((Position) o).i) {
+                return -1;
+            } else if (i > ((Position) o).i) {
+                return 1;
+            }
+        }
+        return 0;
+    }
 }
diff --git a/src/main/java/org/ntlab/acanthus_server/entities/Stroke.java b/src/main/java/org/ntlab/acanthus_server/entities/Stroke.java
index bf88d02..6e1fecf 100644
--- a/src/main/java/org/ntlab/acanthus_server/entities/Stroke.java
+++ b/src/main/java/org/ntlab/acanthus_server/entities/Stroke.java
@@ -1,7 +1,7 @@
 package org.ntlab.acanthus_server.entities;
 
-import java.util.ArrayList;
-import java.util.HashMap;
+import java.util.*;
+
 import org.ntlab.acanthus_server.resources.gallery.StrokesRest;
 import org.ntlab.acanthus_server.entities.Position;
 
@@ -10,7 +10,7 @@
     private int pen;       // ペンの種類
     private int color;     // ペンの色
     private int thickness; // ペンの厚さ
-    private ArrayList<Position> positions = new ArrayList<>();
+    private SortedSet<Position> positions = new TreeSet<>();
 
     public int getStrokeNo() {
         return this.strokeNo;
@@ -26,7 +26,7 @@
     }
 
     //座標のリストを返す
-    public ArrayList<Position> getPositions() {
+    public SortedSet<Position> getPositions() {
         return this.positions;
     }
 
diff --git a/src/main/java/org/ntlab/acanthus_server/resources/gallery/StrokesRest.java b/src/main/java/org/ntlab/acanthus_server/resources/gallery/StrokesRest.java
index a7999a8..f27d813 100644
--- a/src/main/java/org/ntlab/acanthus_server/resources/gallery/StrokesRest.java
+++ b/src/main/java/org/ntlab/acanthus_server/resources/gallery/StrokesRest.java
@@ -7,6 +7,9 @@
 import javax.ws.rs.*;
 import javax.ws.rs.core.MediaType;
 import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.SortedSet;
 
 // _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
 //
@@ -128,11 +131,19 @@
     @Path("/{aid}/pageMap/{pid}/layers/{layerNo}/strokes/{strokeNo}/positions")
     @GET
     @Produces(MediaType.APPLICATION_JSON)
-    public ArrayList<Position> getPositions(@PathParam("aid") Integer aid, @PathParam("pid") Integer pid,
+    public SortedSet<Position> getPositions(@PathParam("aid") Integer aid, @PathParam("pid") Integer pid,
                                             @PathParam("layerNo") Integer layerNo, @PathParam("strokeNo") Integer strokeNo) {
         var pages = gallery.getAnimationByAid(aid).getPages();
         var strokes = pages.get(pid).getLayers().get(layerNo).getStrokes();
 
+/*        Collections.sort(strokes.get(strokeNo).getPositions(), new Comparator() {
+
+            @Override
+            public int compare(Object o1, Object o2) {
+                return 0;
+            }
+        });*/
+
         return strokes.get(strokeNo).getPositions();          // 呼び出したstrokesの情報を返す
 //        if(animation != null) {
 //            return this.positions;
@@ -163,11 +174,11 @@
         position.setXY(positionNo, x, y);
         strokes.get(strokeNo).addPosition(position);          // 呼び出したstrokesに座標を追加する
 //        if(animation != null) {
-//            this.Position.setXY(x, y);
-//            this.positions.add(this.Position);
-//        }else{
-//            throw new WebApplicationException(401);
-//        }
+////            this.Position.setXY(x, y);
+////            this.positions.add(this.Position);
+////        }else{
+////            throw new WebApplicationException(401);
+////        }
         return strokes.get(strokeNo).getPositions().size();
     }
 }