PURPOSE: To increase the suction force of a lead by forming a swollen part directed to a counter contact surface in a fixed contact so as to increase the facing surface between the contact surface of the fixed contact and the other end of the lead.

CONSTITUTION: A fixed contact 24, 25 of magnetic material is of a basic form consisting of a cubic base part 24a, 25a of an almost similar length to the lateral width of a containing part 21f connected with a protruding part 24b, 25b of an almost similar length of the lateral width of a lead 3 at the center of a facing surface. The fixed contacts 24, 25 are disposed vertically along the containing part 21f with a predetermined interval (g) between the end surfaces of the protruding parts 24b, 25b. The fixed contacts 24, 25 has swollen parts 24e, 25e penetrating into a cylindrical part 21a of a coil frame close to contact surfaces including the facing contact surfaces 24c, 25d. In this constitution, the facing surface between the contact surfaces of the fixed contacts and the other end 3b of a lead 3 can be set large, thereby the suction force of the lead can be increased.