Abstract: The optical switch according to the present invention momentarily switches the optical transmission lines made of tapes in which optical fibers are laid parallel to each other. This optical switch has a main body provided at the top thereof with a plug chamber in which a stationary and moving plugs in which the end portions of the optical fibers are fixed so as to abut each other are received, and a sliding mechanism provided on the moving plug. Also, the optical switch has charged in the plug chamber thereof with an oil for reducing the connecting loss, and it has an oil-leak preventive mechanism to prevent the oil from leaking from the hole in which the push pin pressing the moving plug is inserted. Further, the optical switch is provided with a lateral-pressure adjusting mechanism which appropriately gives a lateral pressure to the moving plug by means of the push pin. Furthermore, the optical switch has a cushion mechanism to accommodate a fine vibration or the like caused as the moving plug is moved.