To protect a monitor mechanism, which is installed to receive image or sound from monitor equipment, or control the monitor, etc., from the surge of thunderbolt.

A monitor system is made of a monitor mechanism B comprising monitor equipment (A) composed of an outdoor monitoring camera 1 attached to a pylon 91, a radio 2, etc., video monitors 31 and 33 connected to this monitor mechanism (A) and projecting the image from the camera 1, controllers 32 and 34 for controlling the monitor equipment (A), and others. On the other hand, a time switch 8 is interposed in the relay 7 which electrically connects it with a power source 6 so as to make these monitor equipment (A) and monitor mechanism (B) function as specified, and the distribution line 7 is disconnected by automatically operating this time switch 8 in preset time zone.