To easily and securely install a monitor device.

Responding to sending a flame by a flame sensor 20, a monitor device 11 performs an electronic flash photography by a film unit 22 with a lens. In the front of a photography side, a mirror 16 is fitted and the photographic range of the film unit 22 with the lens can be specified by observing an image reflected by the mirror 16 from the front side. Further, a lock 19 is provided to a lid 18 for replacing the film unit 22 with the lens for prevention against mischief and theft, and a magnet chuck 30 is switched to an attraction state associatively with the locking of the opening/closing operation of the lid 18 locked with a key 20.