To prevent a battery from being consumed due to a careless operation of a charging switch.

A power switch 32 constituted of a fixed armature 36 and an elastic armature 37 is arranged on a circuit board 30 for a stroboscope. A switch pressing piece 34a is arranged on a control plate 34 on which an operation knob 13 is integrally arranged, and the leading end of the switch pressing piece 34a is brought into contact with the elastic armature 37. A recess 37b is formed within a fixed extent so as to adjoin a curved part 37a formed on the root side of the elastic armature 37. When the operation knob 13 is in an OFF position, the switch pressing piece 34a comes in contact with the recess 37a. At the initial stage of moving the operation knob 13 from the OFF position to the ON position, the switching pressing piece 34a simply moves above the recess 37a, then, the elastic armature 37 is not deformed and the power switch is left in the OFF state. When the operation knob 13 is moved more than half, the leading end of the elastic armature 37 comes into contact with the fixed armature 36, and the power switch 32 is turned on.