Abstract: A projection exposure apparatus on which are placed a reticle whose pattern is comprised of an area transmitting a radiation therethrough and an area not transmitting the radiation therethrough and a substrate includes a projection optical system for projecting the pattern formed on the reticle onto the substrate, the projection optical system being telecentric on the substrate side, a device producing a radiation beam for alignment of the reticle and the substrate, an alignment device for supplying the radiation beam onto the substrate through the reticle and the projection optical system and detecting the relative positional relation between the reticle and the substrate through the projection optical system, a device for imparting displacement to the projection optical system to the position of incidence of the radiation beam onto the projection optical system by the alignment device, a device for outputting a position signal conforming to the relative position of the optic axis of the projection optical s