PURPOSE: To obtain the title apparatus not erroneously judging waste refuse as a defect.

CONSTITUTION: A liquid crystal display 3 is arranged on a movable stage 2 and the display pattern generated from a pattern generator 10 is displayed on the liquid crystal display 3 and the movable stage 2 is moved in one direction and the display pattern on the liquid crystal display 3 is read by a CCD unit 4. A personal computer 5 discriminates the coincidence of the read value and standard data and judges the pixel appearing when the pixel data at the time of the display of black becomes white from black and the pixel data at the time of the reversal display of white becomes white from white as waste refuse to discriminate the same from a deflective pixel.