In a pattern inspecting apparatus, images of places which can be expected to be the same pattern are compared with one another. However, a comparison of images obtained by different stage scans and the occurrence of a place capable of being inspected only once lead to a deterioration in the performance of detecting various error defects and an area incapable of being inspected, respectively. For solving this problem, defects detected in a high sensitivity condition are regarded as defect candidates and a critical threshold value, used as a boundary to detect a smaller value as a defect, of a defect candidate portion is obtained by an image processing circuit or an image of the defect candidate portion is obtained by processing with software. Further, the critical threshold value thus obtained is compared with plural threshold values, thereby permitting plural inspection results to be obtained in a single inspection.