The invention is to offer an optical device which is capable of reducing the insertion loss comparing with a conventional one. The optical switch comprises a fiber collimator for input an light beam, a fiber collimator for output the light beam to the outside, an optical path switching element, an optical path switching element as well as a slider arranged in the optical paths between the fiber collimator and the fiber collimator to change the light path and the optical characteristics, a solenoid actuator for moving the slider, a guide mechanism for guiding the slider as the slider moves, a magnet for generating a magnetic field, the magnet being arranged at a position where the slider is pressed against the guide mechanism by means of a magnetic force of a magnetic field generated by the magnet.