diff --git a/org.ntlab.traceAnalyzer/src/org/ntlab/deltaExtractor/DeltaExtractor.java b/org.ntlab.traceAnalyzer/src/org/ntlab/deltaExtractor/DeltaExtractor.java
index 2f896fe..d7a16df 100644
--- a/org.ntlab.traceAnalyzer/src/org/ntlab/deltaExtractor/DeltaExtractor.java
+++ b/org.ntlab.traceAnalyzer/src/org/ntlab/deltaExtractor/DeltaExtractor.java
@@ -797,6 +797,7 @@
 	 * @return ���o����
 	 */
 	public ExtractedStructure extract(TracePoint creationTracePoint) {
+		creationTracePoint = creationTracePoint.duplicate();
 		Statement statement = creationTracePoint.getStatement();
 		if (statement instanceof FieldUpdate) {
 			Reference targetRef = ((FieldUpdate)statement).getReference();