diff --git a/org.ntlab.traceAnalyzer/src/org/ntlab/deltaExtractor/DeltaExtractorJSON.java b/org.ntlab.traceAnalyzer/src/org/ntlab/deltaExtractor/DeltaExtractorJSON.java
index 4b1b293..ff9da6a 100644
--- a/org.ntlab.traceAnalyzer/src/org/ntlab/deltaExtractor/DeltaExtractorJSON.java
+++ b/org.ntlab.traceAnalyzer/src/org/ntlab/deltaExtractor/DeltaExtractorJSON.java
@@ -120,10 +120,13 @@
 										
 					if (ownerObjectId.equals(thisObjectId)) {
 						// �t�B�[���h�Q�Ƃ̏ꍇ
-						removeList.add(refObjectId);
-						existsInFields++;					// set�������get�����o���Ă���”\��������
-						removeList.add(thisObjectId);		// ��ň�U�AthisObject ����菜��						
-						aliasList.put(refObjectId, new Alias(Alias.AliasType.FIELD, 0, refObjectId, tracePoint.duplicate()));
+						if (!removeList.contains(refObjectId)) {
+							// ��ԋ߂��t�B�[���h�Q�Ƃ�D�悷��
+							removeList.add(refObjectId);
+							removeList.add(thisObjectId);		// ��ň�U�AthisObject ����菜��
+							aliasList.put(refObjectId, new Alias(Alias.AliasType.FIELD, 0, refObjectId, tracePoint.duplicate()));
+							existsInFields++;					// set�������get�����o���Ă���”\��������
+						}
 					} else {
 						// ���ڎQ�Ƃ̏ꍇ
 						boolean isSrcSideChanged = false;
@@ -593,10 +596,10 @@
 		if (methodExecution.isCollectionType()) {
 			if (objectId != null) {
 				if (methodExecution.getSignature().contains("Collections.unmodifiable") 
-						|| methodExecution.getSignature().startsWith("Collections.checked") 
-						|| methodExecution.getSignature().startsWith("Collections.synchronized") 
-						|| methodExecution.getSignature().startsWith("Arrays.asList") 
-						|| methodExecution.getSignature().startsWith("Arrays.copyOf")) {
+						|| methodExecution.getSignature().contains("Collections.checked") 
+						|| methodExecution.getSignature().contains("Collections.synchronized") 
+						|| methodExecution.getSignature().contains("Arrays.asList") 
+						|| methodExecution.getSignature().contains("Arrays.copyOf")) {
 					// �z���R���N�V�����̊Ԃ̕ϊ��̏ꍇ�A�ϊ����̑������Ɉˑ�����
 					if (arguments.size() > 0) {
 						if (objectId.equals(srcObject.getId())) {