The invention is directed to find a false defect from defect candidates and obtain a threshold with which the false defect can be eliminated by the smallest number of review times. Defect candidates are reviewed and selected as a defect or a false defect. By deleting a defect candidate having a characteristic quantity equal to or less than that of the false defect from a map or displaying it in another sign, the false defect can be determined visually. Since the defect candidate having the characteristic quantity equal to or less than that of the selected false defect is deleted from the map or displayed in another sign, the defect candidates unnecessary to set a threshold are not reviewed. The number of defect candidates to be reviewed can be largely reduced as compared with that in the conventional technique. Further, by repeating the above work, the threshold is automatically calculated, and an inspection result map with the threshold is displayed, so that a re-inspection is unnecessary.