A measurement apparatus which illuminates a pattern inserted on the object plane of an optical system, and measures a light intensity distribution corresponding to the pattern formed on the image plane of the optical system includes a sensor. The sensor includes a light-shielding member having a slit and a plurality of light-receiving units, wherein the light-shielding member is inserted on the image plane of the optical system and rotates and scans, and the plurality of light-receiving units receive light transmitted through the slit. The measurement apparatus controls rotation of the light-shielding member, on the basis of the positional relationship between the plurality of light-receiving units, and the phase differences between the signals detected by the plurality of light-receiving units arising from the scan of the light-shielding member.