In an inspection apparatus for inspecting an inspection target device formed on an inspection object, the inspection target device is a back-illuminated imaging device into which light is incident from a rear surface opposite to a side of a wiring layer. The inspection apparatus includes a stage having the inspection object placed such that the inspection object faces the rear surface. The stage includes a light transmitter made of a light-transmissive material. The inspection object is placed on the light transmitter below which a light illuminator is disposed. The light illuminator includes a flat light guide plate having a facing surface facing the inspection object. A light source is provided laterally outside the light guide plate configured to diffuse light emitted from the light source incident from a side end surface of the light guide plate, and to emit the light as planar light from the facing surface.