PURPOSE: To provide a reduction-type projection aligner which makes an exposure region large and which can obtain high resolution performance so as to correspond to various circuit patterns.

CONSTITUTION: Exposure light from light source 51 is incident on a photomask 53 via apertures 1, 2 for light-source shaping. Slit-shaped light radiation parts 3, 4 are formed in the individual apertures 1, 2. Regarding the aperture 1, a plurality of light-radiation parts 3 whose position is different are formed. As a result, when the aperture 1 is selected and replaced, the exposure light from the light source 51 can be made incident on the photomask 53 at an optimum angle of incidence. The exposure light is diffracted by a circuit pattern on the mask 53, and zero-order diffracted light α and π first-order diffracted light βare generated. The diffracted light α and the diffracted light β are converged through a pupil 54a in a projection lens 54, and the circuit pattern on the mask 53 is image-formed on the surface of a wafer 55. At this time, the mask 53 and the wafer 55 are synchronously scanned in the direction of an arrow Y by a lens scanning system.