diff --git a/Assets/VRM10/Editor/Components/Constraint/IVRM10ConstraintSourceDestinationExtensions.cs b/Assets/VRM10/Editor/Components/Constraint/IVRM10ConstraintSourceDestinationExtensions.cs
new file mode 100644
index 000000000..38e3c6a0b
--- /dev/null
+++ b/Assets/VRM10/Editor/Components/Constraint/IVRM10ConstraintSourceDestinationExtensions.cs
@@ -0,0 +1,59 @@
+using UnityEditor;
+using UnityEngine;
+
+namespace UniVRM10
+{
+    public static class IVRM10ConstraintSourceDestinationExtensions
+    {
+        public static void DrawSourceCoords(this IVRM10ConstraintSourceDestination self)
+        {
+            try
+            {
+                self.GetSourceCoords().Draw(0.2f);
+            }
+            catch (ConstraintException)
+            {
+
+            }
+        }
+        public static void DrawSourceCurrent(this IVRM10ConstraintSourceDestination self)
+        {
+            try
+            {
+                Handles.matrix = self.GetSourceCurrent().TRS(0.05f);
+                Handles.color = Color.yellow;
+                Handles.DrawWireCube(Vector3.zero, Vector3.one);
+            }
+            catch (ConstraintException)
+            {
+
+            }
+        }
+
+        public static void DrawDstCoords(this IVRM10ConstraintSourceDestination self)
+        {
+            try
+            {
+                self.GetDstCoords().Draw(0.2f);
+            }
+            catch (ConstraintException)
+            {
+
+            }
+        }
+
+        public static void DrawDstCurrent(this IVRM10ConstraintSourceDestination self)
+        {
+            try
+            {
+                Handles.matrix = self.GetDstCurrent().TRS(0.05f);
+                Handles.color = Color.yellow;
+                Handles.DrawWireCube(Vector3.zero, Vector3.one);
+            }
+            catch (ConstraintException)
+            {
+
+            }
+        }
+    }
+}
diff --git a/Assets/VRM10/Editor/Components/Constraint/IVRM10ConstraintSourceDestinationExtensions.cs.meta b/Assets/VRM10/Editor/Components/Constraint/IVRM10ConstraintSourceDestinationExtensions.cs.meta
new file mode 100644
index 000000000..a2836e116
--- /dev/null
+++ b/Assets/VRM10/Editor/Components/Constraint/IVRM10ConstraintSourceDestinationExtensions.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 59e1ae1f9d4fb9a459cd2c97a4351b1f
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Assets/VRM10/Editor/Components/Constraint/VRM10RotationConstraintEditor.cs b/Assets/VRM10/Editor/Components/Constraint/VRM10RotationConstraintEditor.cs
index 317ceddda..c0503738c 100644
--- a/Assets/VRM10/Editor/Components/Constraint/VRM10RotationConstraintEditor.cs
+++ b/Assets/VRM10/Editor/Components/Constraint/VRM10RotationConstraintEditor.cs
@@ -1,4 +1,3 @@
-using System;
 using System.Text;
 using UnityEditor;
 using UnityEngine;
@@ -15,39 +14,18 @@ namespace UniVRM10
             m_target = (VRM10RotationConstraint)target;
         }
 
-        #region SRC
-        void DrawSourceCurrent()
-        {
-            var s = m_target.transform.lossyScale.x;
-            Handles.matrix = m_target.GetSourceCurrent().TRS(0.05f * s);
-            Handles.color = Color.yellow;
-            Handles.DrawWireCube(Vector3.zero, Vector3.one);
-        }
-
-        void DrawSourceCoords()
-        {
-            var s = m_target.transform.lossyScale.x;
-            m_target.GetSourceCoords().Draw(0.2f / s);
-        }
-        #endregion
-
-        #region Dst
-        void DrawDstCurrent()
-        {
-            var s = m_target.transform.lossyScale.x;
-            Handles.matrix = m_target.GetDstCurrent().TRS(0.05f * s);
-            Handles.color = Color.yellow;
-            Handles.DrawWireCube(Vector3.zero, Vector3.one);
-        }
-
-        void DrawDstCoords()
-        {
-            var s = m_target.transform.lossyScale.x;
-            m_target.GetDstCoords().Draw(0.2f / s);
-        }
-        #endregion
-
         static GUIStyle s_style;
+        static GUIStyle Style
+        {
+            get
+            {
+                if (s_style == null)
+                {
+                    s_style = new GUIStyle("box");
+                }
+                return s_style;
+            }
+        }
 
         /// <summary>
         /// Euler各を +- 180 にクランプする
@@ -74,16 +52,12 @@ namespace UniVRM10
             {
                 return;
             }
-            if (s_style == null)
-            {
-                s_style = new GUIStyle("box");
-            }
 
             // this to target line
             Handles.color = Color.yellow;
             Handles.DrawLine(m_target.Source.position, m_target.transform.position);
 
-            var euler = Clamp180(m_target.Delta.eulerAngles);
+            var delta = Clamp180(m_target.Delta.eulerAngles);
 
             // show source
             {
@@ -91,26 +65,26 @@ namespace UniVRM10
                 sb.AppendLine();
                 sb.AppendLine();
                 sb.AppendLine($"source: {m_target.SourceCoordinate}");
-                sb.AppendLine($"{euler.x:0.}");
-                sb.AppendLine($"{euler.y:0.}");
-                sb.Append($"{euler.z:0.}");
-                Handles.Label(m_target.Source.position, sb.ToString(), s_style);
+                sb.AppendLine($"{delta.x:0.}");
+                sb.AppendLine($"{delta.y:0.}");
+                sb.Append($"{delta.z:0.}");
+                Handles.Label(m_target.Source.position, sb.ToString(), Style);
             }
 
             // show dst
             {
                 var sb = new StringBuilder();
                 sb.AppendLine($"constraint: {m_target.DestinationCoordinate}");
-                sb.AppendLine(m_target.FreezeAxes.HasFlag(AxisMask.X) ? $"freeze" : $"{euler.x:0.}");
-                sb.AppendLine(m_target.FreezeAxes.HasFlag(AxisMask.Y) ? $"freeze" : $"{euler.y:0.}");
-                sb.Append(m_target.FreezeAxes.HasFlag(AxisMask.Z) ? $"freeze" : $"{euler.z:0.}");
-                Handles.Label(m_target.transform.position, sb.ToString(), s_style);
+                sb.AppendLine(m_target.FreezeAxes.HasFlag(AxisMask.X) ? $"freeze" : $"{delta.x:0.}");
+                sb.AppendLine(m_target.FreezeAxes.HasFlag(AxisMask.Y) ? $"freeze" : $"{delta.y:0.}");
+                sb.Append(m_target.FreezeAxes.HasFlag(AxisMask.Z) ? $"freeze" : $"{delta.z:0.}");
+                Handles.Label(m_target.transform.position, sb.ToString(), Style);
             }
 
-            DrawSourceCoords();
-            DrawSourceCurrent();
-            DrawDstCoords();
-            DrawDstCurrent();
+            m_target.DrawSourceCoords();
+            m_target.DrawSourceCurrent();
+            m_target.DrawDstCoords();
+            m_target.DrawDstCurrent();
         }
     }
 }
diff --git a/Assets/VRM10/Runtime/Components/Constraint/IVRM10SourceDestination.cs b/Assets/VRM10/Runtime/Components/Constraint/IVRM10SourceDestination.cs
new file mode 100644
index 000000000..d6aa2ca89
--- /dev/null
+++ b/Assets/VRM10/Runtime/Components/Constraint/IVRM10SourceDestination.cs
@@ -0,0 +1,11 @@
+namespace UniVRM10
+{
+    public interface IVRM10ConstraintSourceDestination
+    {
+        TR GetSourceCoords();
+        TR GetSourceCurrent();
+
+        TR GetDstCoords();
+        TR GetDstCurrent();
+    }
+}
diff --git a/Assets/VRM10/Runtime/Components/Constraint/IVRM10SourceDestination.cs.meta b/Assets/VRM10/Runtime/Components/Constraint/IVRM10SourceDestination.cs.meta
new file mode 100644
index 000000000..ff49caec8
--- /dev/null
+++ b/Assets/VRM10/Runtime/Components/Constraint/IVRM10SourceDestination.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 4d1ea0f0f4d95a2499f9aa5a1d7a2235
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Assets/VRM10/Runtime/Components/Constraint/VRM10RotationConstraint.cs b/Assets/VRM10/Runtime/Components/Constraint/VRM10RotationConstraint.cs
index 24c80d31d..635ff3782 100644
--- a/Assets/VRM10/Runtime/Components/Constraint/VRM10RotationConstraint.cs
+++ b/Assets/VRM10/Runtime/Components/Constraint/VRM10RotationConstraint.cs
@@ -9,7 +9,7 @@ namespace UniVRM10
     /// 対象の初期回転と現在回転の差分(delta)を、自身の初期回転と自身の初期回転にdeltaを乗算したものに対してWeightでSlerpする。
     /// </summary>
     [DisallowMultipleComponent]
-    public class VRM10RotationConstraint : VRM10Constraint
+    public class VRM10RotationConstraint : VRM10Constraint, IVRM10ConstraintSourceDestination
     {
         [SerializeField]
         public Transform Source = default;
@@ -36,10 +36,6 @@ namespace UniVRM10
 
         ConstraintSource m_src;
 
-        /// <summary>
-        /// Source の座標系
-        /// </summary>
-        /// <returns></returns>
         public TR GetSourceCoords()
         {
             switch (SourceCoordinate)