diff --git a/app/src/main/java/org/ntlab/radishforandroidstudio/framework/RWT/RWTLayers.java b/app/src/main/java/org/ntlab/radishforandroidstudio/framework/RWT/RWTLayers.java
index c45d137..9a3c9df 100644
--- a/app/src/main/java/org/ntlab/radishforandroidstudio/framework/RWT/RWTLayers.java
+++ b/app/src/main/java/org/ntlab/radishforandroidstudio/framework/RWT/RWTLayers.java
@@ -5,12 +5,19 @@
 import org.ntlab.radishforandroidstudio.java3d.GraphicsContext3D;
 
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.TreeMap;
 
 public class RWTLayers {
-    private TreeMap<Integer, ArrayList<RWTLayer>> layers = new TreeMap();
+    private TreeMap<Integer, ArrayList<RWTLayer>> layers = new TreeMap(
+            new Comparator<Integer>() {
+                public int compare(Integer m, Integer n){
+                    return ((Integer)m).compareTo(n) * -1;
+                }
+            }
+    );
 
     public RWTLayers() {