diff --git a/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/MethodExecution.java b/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/MethodExecution.java
index c16140c..1b581d2 100644
--- a/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/MethodExecution.java
+++ b/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/MethodExecution.java
@@ -268,13 +268,9 @@
 	 * @return �����œn���ꂽmethodExecution���Ăяo�������Ƃ��L�^���Ă��郁�\�b�h�Ăяo��
 	 */
 	public MethodInvocation getMethodInvocation(MethodExecution child) {
-		for (Statement statement : statements) {
-			if (statement instanceof MethodInvocation) {
-				MethodExecution calledMethodExecution = ((MethodInvocation)statement).getCalledMethodExecution();
-				if (calledMethodExecution.equals(child)) {
-					return (MethodInvocation)statement;
-				}
-			}
+		int callerStatementExecution = child.getCallerStatementExecution();
+		if (callerStatementExecution != -1) {
+			return (MethodInvocation)statements.get(callerStatementExecution);			
 		}
 		return null;
 	}
diff --git a/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/TraceJSON.java b/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/TraceJSON.java
index a8231c8..9fd4929 100644
--- a/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/TraceJSON.java
+++ b/org.ntlab.traceCollector/src/org/ntlab/traceCollector/tracer/trace/TraceJSON.java
@@ -844,7 +844,7 @@
 		if (getInstance().thread != null) getInstance().thread.blockEnter(Integer.parseInt(blockId), Integer.parseInt(incomings), Integer.parseInt(lineNum), timeStamp);
 	}
 
-	public static ThreadInstance getThreadInstanceForDebuggingControl(String threadId) {
+	public static ThreadInstance getThreadInstance(String threadId) {
 		return getInstance().threads.get(threadId);
 	}
 	
@@ -875,12 +875,15 @@
 	 * @param thread
 	 * @return
 	 */
-	public static FieldUpdate getRecentlyFieldUpdateForDebuggingControl(String containerObjId, String fieldName, Thread thread) {
+	public static FieldUpdate getRecentlyFieldUpdate(String containerObjId, String fieldName, Thread thread) {
 		TracePoint before = getCurrentTracePoint(thread);
 		if (!before.isValid()) {
 			before.stepBackOver();
+			if (!before.isValid()) {
+				return null; // �t�����T���ł���ȏ�H��Ȃ������ꍇ(root���\�b�h���s��1�s�ڂȂ�)�@���ꂪ�Ȃ��Ǝ��s����TimeoutException�ŗ�����
+			}
 		}
-		TracePoint tp = getFieldUpdateTracePointForDebuggingControl(containerObjId, fieldName, before);
+		TracePoint tp = getFieldUpdateTracePoint(containerObjId, fieldName, before);
 		if (tp != null && tp.getStatement() instanceof FieldUpdate) {
 			return (FieldUpdate)tp.getStatement();				
 		}
@@ -895,7 +898,7 @@
 	 * @param before
 	 * @return
 	 */
-	public static TracePoint getFieldUpdateTracePointForDebuggingControl(final String containerObjId, final String fieldName, TracePoint before) {		
+	public static TracePoint getFieldUpdateTracePoint(final String containerObjId, final String fieldName, TracePoint before) {		
 		before = before.duplicate();
 		before = getInstance().traverseStatementsInTraceBackward(new IStatementVisitor() {
 			@Override
@@ -926,12 +929,15 @@
 	 * @param thread
 	 * @return
 	 */
-	public static ArrayUpdate getRecentlyArrayUpdateForDebuggingControl(String arrayObjId, int index, Thread thread) {
+	public static ArrayUpdate getRecentlyArrayUpdate(String arrayObjId, int index, Thread thread) {
 		TracePoint before = getCurrentTracePoint(thread);
 		if (!before.isValid()) {
 			before.stepBackOver();
+			if (!before.isValid()) {
+				return null; // �t�����T���ł���ȏ�H��Ȃ������ꍇ(root���\�b�h���s��1�s�ڂȂ�)�@���ꂪ�Ȃ��Ǝ��s����TimeoutException�ŗ�����
+			}
 		}
-		TracePoint tp = getArrayUpdateTracePointForDebuggingControl(arrayObjId, index, before);
+		TracePoint tp = getArrayUpdateTracePoint(arrayObjId, index, before);
 		if (tp != null && tp.getStatement() instanceof ArrayUpdate) {
 			return (ArrayUpdate)tp.getStatement();
 		}
@@ -946,7 +952,7 @@
 	 * @param before
 	 * @return
 	 */
-	public static TracePoint getArrayUpdateTracePointForDebuggingControl(final String arrayObjId, final int index, TracePoint before) {		
+	public static TracePoint getArrayUpdateTracePoint(final String arrayObjId, final int index, TracePoint before) {		
 		before = before.duplicate();
 		before = getInstance().traverseStatementsInTraceBackward(new IStatementVisitor() {
 			@Override