An optical element is moved in six-degrees-of-freedom. Three first displacement sensors are disposed on a base plate and measure respective displacement amounts of three mutually different points on the optical element in a first direction. A second displacement sensor measures a displacement amount of one point on the optical element in a second direction. Two third displacement sensors measure respective displacement amounts of two mutually different points on the optical element in a third direction. A transformation processor transforms the six measured displacement amounts. A calibration processor calibrates the transformed displacement amounts with a calibration matrix of which coefficients are previously obtained to calibrate the displacement amounts in the six-degrees-of-freedom, which have errors due to measurement errors of the displacement sensors. A controller outputs command values based on differences between the calibrated displacement amounts and target displacement amounts.