A stage apparatus including a stage capable of moving an object, first and second measurement units adapted to measure a displacement of the stage in a predetermined direction based on a variation of an optical path length of measurement light, which are arranged so as to have an overlap area to simultaneously measure a stage position while the stage is being moved, a switching unit to switch measurement by the first measurement unit to measurement by the second measurement unit by delivering a measurement value from the first measurement unit to the second measurement unit in the overlap area, and a correction unit, in the stage position upon switching by the switching unit, to correct a wavelength variation of the measurement light based on the measurement value delivered from the first measurement unit to the second measurement unit.