Index: /trunk/Include/Classes/System/Threading/Thread.ab
===================================================================
--- /trunk/Include/Classes/System/Threading/Thread.ab	(revision 492)
+++ /trunk/Include/Classes/System/Threading/Thread.ab	(revision 493)
@@ -94,5 +94,13 @@
 	' Public Properties
 	'-----------------------
-
+	Function IsAlive() As Boolean
+		Dim code As DWord
+		GetExitCodeThread(m_hThread,code)
+		If code=STILL_ACTIVE Then
+			Return True
+		Else
+			Return False
+		End If
+	End Function
 	
 	'Priority Property
@@ -155,5 +163,5 @@
 
 		'自身のスレッドハンドルを閉じる
-		CloseHandle(m_hThread)
+		CloseHandle(InterlockedExchangePointer(VarPtr(m_hThread),NULL))
 		m_hThread=0