ALIGNER

PURPOSE:To realize uniform projection imagery in an exposure range, by installing a means offsetting an exposure imagery position inside a wafer surface so as to correspond with the size of an exposure range to be set. CONSTITUTION:A signal is outputted from a controller 15, and sent to a driving circuit 11, which operates driving mechanisms 9a, 9b, thereby moving light shielding plates 6a, 6b to set an exposure range EX. Sensors 10a, 10b send actual position data of the light shielding plates 6a, 6b to a controller 15, via a shielding plate position detecting circuit 12. Whether the shielding plates 6a, 6b are set at correct positions is recognized. When the positions of the light shielding plates 6a, 6b are deviated, a signal for correcting the deviations is outputted, and the plates 6a, 6b are set at the correct positions. The offset amount Z with which the exposure range EX corresponds is taken in from a focus position offset storage part 14. The controller 15 outputs a signal for moving a Z-axis driving part 4 by that amount to a Z-axis driving circuit 16, and a wafer 3 mounted on the Z-axis driving part 4 is moved up to the position where the offset amount Z is obtained.