A plurality of surface images are picked up while changing a relative posture of a surface of an object to be inspected with respect to an image pickup part configured to pick up an image of the surface of the object to be inspected under a state in which the surface of the object to be inspected is irradiated with light, and a defect and luminance unevenness of the surface of the object to be inspected are discriminated from each other based on a change in the plurality of surface images.