coil 102 is wound around it the second arm of the u shaped yoke 103 extends upward along the side surface of the substrate 101 two moving springs 401 and 402 are electrically insulated from the yoke 103 and one end of each is attached to an upper part of the second arm of the u shaped yoke 103 the other ends of the moving springs 401 and 402 are bent at a right angle in a direction toward the first arm of the yoke 103 and so as to extend horizontally beyond the first arm incidentally respective end portions 401 a and 401 b of the moving springs 401 and 402 extend downward beyond the bottom of the u shaped yoke 103 and are respectively connected to a first common terminal not shown and a second common terminal 404 an armature 107 is attached to the moving springs 401 and 402 through an insulating member 403 by caulking members 106 incidentally the armature 107 is sized so that one edge of the armature 107 contacts with the second arm of the u shaped yoke 103 and that the armature 107 covers the first arm of the u shaped yoke 103 that is the armature 107 closes an.