To prevent impact from being given to an operation knob for switching on/off a power switch for a stroboscope, and also, to prevent the trouble and failure of the power switch even if the impact is given to the knob.

An opening is formed in a front cover 17, and the operation knob 10 is made to project ahead from the opening. An opening 5a for exposing a photographic lens 4 is formed in the front cover 17, and a raised part 5 is formed around the opening 5a. Assuming a contact surface S where the front end of the raised part 5 comes into contact with the receiving part 40 on the operation knob side on the front cover 17, the projection height of the operation knob 10 is set so that the front end part of the operation knob 10 may not reach the contact surface S. Viewing from the front side of the front cover 17, the power switch is positioned outside the external outline of the operation knob 10. As the operation knob 10 is slid to an ON position, an operating member 31 is moved together with the knob 10, and then, an elastic armature 29b is bent so as to turn on the power switch.