To provide a monitoring device with which patrolling persons do not have to be increased by reducing the number of photographing times of an illegally dumping person (vehicle) at a time to reduce film exchange frequency and reducing the number of patrolling times for film exchange.

A plurality of detection zones are provided within a monitoring area in each fixed interval, a pyroelectric infrared sensor 4 is provided for transmitting a detection signal to a controller 8 each time a person or vehicle goes into the monitoring area to cross a detection zone, the controller 8 outputs a control signal to a camera 3 when the detection signal is transmitted two times in one detection zone within a set time, a shutter 3a and strobe 3b are made to go along with each other to perform photographing, and when single photographing is finished, photographing is prevented, for instance, after one hour so that photographing is performed only one time about single illegal dumping.