PURPOSE: To attain high reliability by a method wherein two elements are picked up with dark-field illumination from one direction, an inclined part of a pattern detected with the illumination in that direction is set to be an inspection prohibition area, and then two images are subjected to comparative inspection by switching the direction of the illumination.

CONSTITUTION: A construction is made so that dark-field illumination from a light source 10 can be switched over to the right and left by two kinds of light-intercepting parts provided in a light-intercepting plate 12. Next, one light- intercepting part is inserted into an optical path, one element on a wafer 17 is picked up by a TV camera 16 and an output thus obtained is stored in a memory 20a, while a pickup output obtained through the other light-intercepting part is stored in a memory 20b. Subsequently another element on the wafer 17 is picked up in the same way and outputs are stored in memories 20c and 20d respectively. Then, four images stored in the memories 20aW20d are inputted to a defect judging circuit 40, the images of the two elements are compared with each other while the inclined part of a pattern detected brightly is set to be an inspection prohibition area, and a massive particulate is detected thereby. Accordingly, detection can be executed with high reliability.