Two stages (WS1, WS2) holding wafers can independently move between a positional information measuring section (PIS) under an alignment system (24a) and an exposing section (EPS) under a projection optical system (PI). The wafer exchange and alignment are performed on the stage (WS1), during which wafer (W2) is exposed on the stage (WS2). A position of each shot area of wafer (WS1) is obtained as a relative position with respect to a reference mark formed on the stage WS1 in the section (PIS). Relative positional information can be used for the alignment with respect to an exposure pattern when the wafer (WS1) is moved to the section (EPS) to be exposed. Therefore, it is not necessary that a stage position is observed continuously in moving the stage. Exposure operations are performed in parallel by the two wafer stages (WS1) and (WS2) so as to improve the throughput.