There is disclosed an inspection device for inspecting a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually, said inspection device comprising, a conjugate optical system which is arranged optically downstream the spatial light modulator and which forms a conjugate plane optically conjugate with an array plane where the plurality of optical elements are arrayed, a photodetector having a detection surface arranged on or near the conjugate plane, and an inspection unit which inspects optical characteristics of the plurality of optical elements, based on a result of detection by the photodetector.