A stage device is equipped with two stages that can move along an XY plane above a stage base, a first magnet unit and a second magnet unit provided in the two stages, respectively, a planar motor which has a coil unit including a plurality of coils arranged two-dimensionally above the stage base that drives the two stages by a driving force generated by electromagnetic interaction with each of the first magnet unit and the second magnet unit. In a state where the two stages are in proximity within a predetermined distance or in contact with each other above the stage base in a Y-axis direction, a layout of magnets is decided so that no magnets structuring the first magnet unit and no magnets structuring the second magnet unit simultaneously face the same coil structuring the coil unit.