A movable contact (6) which is positioned inside a sealing case (1) is moved by a magnetic shunt body (16) which moves outside the sealing case. The movement of the movable contact by the movement of the magnetic shunt body is caused by a change of magnetic force of a magnet (5) through a pair of yokes (3,4). The magnetic shunt body (16) is assembled to a moving member (13), and elastically moves around the moving member resisting a first spring (15).