PURPOSE: To enhance accuracy in the inspection of defect by contriving not to pick up the light leaked from regions other than a target region thereby picking up the light leaked from the target region.

CONSTITUTION: The apparatus for inspecting detect comprises a light source 11 for irradiating an object 15 to be inspected with a light L1, a first shading means 12 for masking one opening 15A made through the object 15, means 13 for detecting the light L2 leaking through the opening 15A, and a second shading means 14 for controlling the shading of light L3 leaking through the region of the object 15 other than the opening 15A. The second shading means 14 is disposed between the light source 11 and the object 15 or between the object 15 and the optical detecting means 13. The second shading means 14 comprises a liquid crystal panel.