1. A device for inspecting an illumination optical device that is adapted to detect a luminous flux emitted from a light source through an illumination optical device to inspect optical characteristics of the illumination optical device, comprising: a holder for holding the illumination optical device as an object to be inspected; and a projection plate on which an optical image of the luminous flux emitted from the illumination optical device held by the holder is projected, wherein a parting frame based on an illumination region of the illumination optical device is formed on the projection plate.