To ensure high-precision pattern transfer without lowering the throughput.

A projection exposure apparatus comprises a reticle stage 33 on which a reticle 31 on whose side walls reflection plates 50X-1, 50X-2, 50Y-1 and 50Y-2 for a reticle are provided is mounted, an X-Y stage 44 on which a wafer 45 is mounted, motors 47 and 48 for moving the X-Y stage 44 in a planar direction, a reduction lens 40, reticle dimension measuring units 52X-1, 52X-2, 52Y-1 and 52Y-2 for detecting the amount of displacement of the reticle 31 by emitting laser beams toward the reflection plates 50X-1, 50X-2, 50Y-1 and 50Y-2 and receiving the laser beams therefrom, and a control unit 60 which positions the reticle 31 and the wafer 45 after displacement based on the amount of displacement of the reticle 31 acquired by the reticle dimension measuring units 52X-1, 52X-2, 52Y-1 and 52Y-2. The positional correction of the wafer and transfer pattern is possible in real time when the reticle is displaced or deformed. It is therefore possible to carry out high-precision projection exposure without lowering the throughput.