diff --git a/Mile.Xaml.Managed/Interop/IInitializeWithWindow.cs b/Mile.Xaml.Managed/Interop/IInitializeWithWindow.cs
new file mode 100644
index 0000000..2250d7d
--- /dev/null
+++ b/Mile.Xaml.Managed/Interop/IInitializeWithWindow.cs
@@ -0,0 +1,23 @@
+/*
+ * PROJECT:   Mouri Internal Library Essentials
+ * FILE:      IInitializeWithWindow.cs
+ * PURPOSE:   Definition for Mile.Xaml.Interop.IInitializeWithWindow
+ *
+ * LICENSE:   The MIT License
+ *
+ * MAINTAINER: MouriNaruto (Kenji.Mouri@outlook.com)
+ */
+
+using System;
+using System.Runtime.InteropServices;
+
+namespace Mile.Xaml.Interop
+{
+    [ComImport]
+    [Guid("3E68D4BD-7135-4D10-8018-9FB6D9F33FA1")]
+    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+    public interface IInitializeWithWindow
+    {
+        void Initialize(IntPtr hwnd);
+    }
+}