To prevent a stroboscope charging switch from projecting and to enhance assembling performance.

A folded piece 52 erected on the surface side of a contact piece 50 is formed at the edge of the supporting part 50b of the piece 50. The supporting part 50 is fitted to a contact piece receiver 51 formed almost similarly to the contour thereof. When the supporting part 50b is fitted to the receiver 51, the tip of the piece 52 bites the inside wall of the receiver 51 so as to prevent the supporting part 50b from being moved in the direction that it is removed from the receiver 51. The inside wall of a front cover 22 is provided with a projection 56b and a supporting piece 57. By the projection 56b, the supporting part 50b is pressed into the receiver 51 so as to be firmly fixed. By the piece 57, the piece 50 is pressed into a main body base part 21 side. Then, a gap is formed between the piece 50 and the stroboscope charging switch 15 so as to prevent pressing force toward the piece 50 on the cover 22 side from influencing the switch 15.