PURPOSE: To reduce the influence of a high duty cycle and to attempt miniaturization by forming structure in which a solenoid having a frame part having end parts which are formed integrally with a wall part and a frame member is mounted between the wall part and the frame member.

CONSTITUTION: A solenoid 46 is assembled and fitted to a mounting bracket 56 by a process in which the end part 96 of a bottom part 50 is put into a groove formed between the third and fourth projections 66, 68 by the projections 66, 68. The upper part 48 of the solenoid 46, when its end part 98 was passed through lugs 78, 80 to be inserted into a groove formed between a frame member 58 and the first projection 64 by them and slid under the groove, the solenoid 46 is rotated slightly, the end part 100 of a part 48 is slid along inclination parts 82, 84, portions 48, 50 is inserted into a groove formed by the member 58 and the projection 64 and a groove formed by the projections 66, 68. The solenoid 46, when the end 100 of the upper part 48 contacts the straight line parts 86, 88 of the lugs 78, 80, is fixed at its place.