A variable spectroscopic element in which a placed position of first sensor and a placed position of the third sensor are symmetrical and a placed position of second sensor and a placed position of fourth sensor are symmetrical with respect to a line connecting the centers of mass of the surfaces of a pair of optical substrates opposite to each other respectively and first to fourth actuators are arranged includes a control unit which calculates a distance between the centers of mass, a first angle that is made between the moved optical substrate and the other optical substrate and a second angle that is made between the other optical substrate and the moved optical substrate, with signals from the first to fourth sensors, and drives the first to fourth actuators on the basis of the distance between the centers of mass, the first angle, and the second angle.