PURPOSE: To regulate the swing of a lever, to miniaturize an electomagnetic adsorbing part, further to steplessly adjusting the lever and to improve fitting workability.

CONSTITUTION: A vertically freely swinging lever 3 is supported by a rotary shaft 8, a large diameter expanded part 13 is formed at an intermediate shaft part 8a of the lever 3, and the lower swing direction side of the lever 3 at the large diameter expanded part 13 is defined as a lower swing regulating plane. On the other hand, an armature 34 supported on the side of a base end so as to be freely swung by an electromagnetic adsorbing part 33 to control the adsorption is provided, the top end side of the armature 34 is abutted to the upper face of the intermediate shaft part 8a of the rotary shaft 8 at the time of downward swing due to the electromagnetic adsorbing part 33, and its top end face 34a is positioned in counter to the lower swing regulating plane 14. At the same time, the height of a core to swing the armature 34 is set higher than the height position in a horizontal tangential direction on the intermediate axis part outer peripheral face of the rotary shaft 8.