PURPOSE: To inspect a surface with high accuracy and high efficiency, by providing a reflecting mirror to allow parallel light for oblique light illumination to be incident to said mirror and allowing the reflected light at this time to be incident to an image sensing part.
CONSTITUTION: This apparatus consists of a holding part 2 for holding and locating a Si-wafer 1 in a freely detachable manner and an illumination part 3 for illuminating the wafer with oblique light, and the holding part 2 consisting of an X-Y table 7 and the reflecting mirror 9 provided to one side part of the upper surface of said table 7. At first, the table 7 is placed at a position where the reflecting mirror 9 comes to the part directly under an ITV camera 13 with respect to the illumination part 3 and parallel beam 10 is projected on the reflecting mirror 9 from the illumination part 3. The light 10 is incident to a reflecting surface 11 of the mirror 9 with the movement of the table 7 and reflected upwardly to sense the image of the reflecting region of the light 10 and an image signal SA is outputted to an operational control part 5. Subsequently, the image signal is converted by an A/D converter and a light quantity abnormality diagnostic means judges whether the voltage value of the signal SA is within a predetermined tolerant region and, on the basis of the quantity of the light 10, the continuation and interruption of inspection are performed.