PROJECTION ALIGNER

PROBLEM TO BE SOLVED: To provide a projection aligner allowing it to avoid exposure in an underset state of a reticule and a sensitive substrate inspite of setting a large- sized and heavy weight substrate stage. SOLUTION: A reticule alignment controller 42 performing a constant servo- driving control of a reticule table 7 and a substrate stage controller 43 performing a driving control of a substrate stage 10 are connected by means of a local interface 30. The substrate stage controller 43 monitors a positioning error of a substrate stage 10 and a positional error of the reticule table 7 obtained through a local interface 30 so as to perform exposure control. Further, the reticule alignment controller 42 monitors a driving state of the substrate stage 10 through the local interface 30 and when the substrate stage 10 is under high-speed driving, gain of servodriving of the reticule table 7 is lowered and stopped.