A variable spectrum element includes: first and third sensors which are placed at positions at which the first and third sensors 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 second and fourth sensors which are placed at positions at which the second and fourth sensors are symmetrical with respect to the line connecting the centers of mass, respectively and first to fourth actuators which are placed on lines running from the center of mass of the surface of each of the pair of the optical substrates opposite to each other to the centers of the first to fourth sensors respectively, respectively.
