To provide a burglar prevention system capable of easily recognizing and changing a guard state, the state of a burglar prevention sensor and an alert area at the time of monitoring many alert areas.

In this burglar prevention system capable of displaying the burglar prevention information of the operation state of the burglar prevention sensor installed in the plural alert areas and alert setting and releasing, etc., at a display device and setting and releasing the alert through a display screen displayed at the display device 6, display is selectively performed at the display device as group alert information for respective monitoring areas divided beforehand and the alert is set and released through the selectively displayed display screen.