To automatize unevenness inspection for a specimen using a detecting means of an optical system to provide an inspection result with high reliability.

A toothed wheel 11 is rotated intermittently along an arrow mark A direction by every very small angle using an electric motor 14. Detecting light is emitted at this time from a light emitting element 15A of an optical sensor 15 toward an uneven part 12 of the toothed wheel 11. The fact that either of a tooth space 12B or a tooth part 12A in the uneven part 12 corresponds to a position irradiated with the light is determined based on the presence of light reception in a light receiving element 15B. Weather the respective tooth parts 12A and the respective spaces 12B satisfy shapes of specifications or not is determined when determined results are switched, so as to discriminate quality, i.e., a non-defective or a defective, of the toothed wheel 11.