PURPOSE: To improve the measuring accuracy by clarifying the profile of the projected image of a defect such as the strain or the flaw of a transparent platelike material to be inspected, and making the change of the profile and the size of the image of the defect scarcely occur on the image even when the image is photographed by photographing means.

CONSTITUTION: The quality inspecting apparatus 10 for a transparent platelike material has a light source 14 arranged in the perpendicular direction to the surface of a transparent plate glass 12 to project parallel beams to the glass 12. A screen 16 for projecting the light passed through the glass 12 is arranged on the opposite side to the source 14 via the glass 12, and formed out of a translucent film. A camera 18 is arranged on the opposite side to the glass 12 via the screen 16, and a defect 12A such as strain or flaw of the glass 12 projected to the screen 16 is photographed.