diff --git a/src/org/ntlab/deltaViewer/MagnetRONViewer.java b/src/org/ntlab/deltaViewer/MagnetRONViewer.java
index 82d2d79..84808f0 100644
--- a/src/org/ntlab/deltaViewer/MagnetRONViewer.java
+++ b/src/org/ntlab/deltaViewer/MagnetRONViewer.java
@@ -83,14 +83,29 @@
 	}
 	
 	public void clear() {
+		mxgraph.getModel().beginUpdate();
+		try {
+			System.out.println("Clear: ");
+			for (ObjectVertex ov: objectToVertexMap.values()) {
+				mxICell ovCell = (mxICell)ov.getCell();
+				if (ovCell != null) {
+					if (!ovCell.getParent().equals(mxDefaultParent)) {
+						// If parent of ObjectVertex cell isn't mxDefaltParent, reset parent.
+						ovCell.getParent().remove(ovCell);
+						ovCell.setParent(mxDefaultParent);
+					}
+				}
+			}
+		} finally {
+			mxgraph.getModel().endUpdate();
+		}
 		objectToVertexMap.clear();
 		methodExecToVertexMap.clear();
 		edgeMap.clear();
 		curFrame = 0;
-		// TODO Fix bug all cells are not remove in ArgoUML Delete.
 		mxgraph.getModel().beginUpdate();
 		try {
-			mxgraph.removeCells(mxgraph.getChildVertices(mxgraph.getDefaultParent()));
+			mxgraph.removeCells(mxgraph.getChildVertices(mxDefaultParent));
 		} finally {
 			mxgraph.getModel().endUpdate();
 		}