An exemplary image processing apparatus comprises: a polarized light source section; an image capturing section which sequentially captures an image of the object that is being illuminated with each of three or more plane polarized light rays; and an image processing section. The image processing section includes: a varying intensity processing section which calculates a state of polarized light reflected from the object's surface; a reflection decision section which distinguishes a multi-reflection region in which incoming light is reflected twice from a recessed region from a once-reflected region in which the incoming light is reflected only once from the object's surface; and a mirror image search section which locates a pair of multi-reflection regions. Based on the pair of multi-reflection regions, the image processing section generates an image representing the recessed region on the object's surface.