There is provided an inspection apparatus which inspects a substrate supporting portion configured to support a substrate during an exposure performed by an exposure apparatus. The apparatus includes: a irradiation unit configured to irradiate, with an illumination light beam, a surface of the substrate on which a pattern has been formed by an exposure by the exposure device; a detecting unit configured to detect reflected light from a pattern in the irradiated surface; a focusing state computation unit connected to the detection unit and configured to determine a focusing state of the pattern of the substrate, based on a detection result of the reflected light beam detected by the detection unit; and an inspection unit connected to the focusing state computation unit and configured to inspect the substrate supporting portion based on the focusing state determined by the focusing state computation unit.