An exposure apparatus for transferring a pattern of an original, having an original mark, onto a substrate having a substrate mark, through a projection optical system. The apparatus includes a movable stage, having a stage mark, for holding the substrate, an optical member having first and second marks and being held fixed with respect to the projection optical system, a first position detecting system having a detection center and for detecting (i) a relative position between the detection center and the stage mark, and (ii) a relative position between the detection center and the substrate mark, and a second position detecting system for detecting (i) a relative position between the stage mark and the first mark of the optical member, and (ii) a relative position between the original mark and the second mark of the optical member. The original can be aligned with respect to the projection optical system on the basis of the relative position of the original mark and the second mark as detected by the second position detecting system. A base line offset can be determined on the basis of the relative position of the detection center and the stage mark as detected by the first position detecting system, and the relative position of the stage mark and the first mark as detected by the second position detecting system. The substrate can be aligned with respect to the projection optical system on the basis of the thus determined base line offset and the relative position of the detection center and the substrate mark as detected by the first position detecting system.