A storage element stores identification information identifying to-be-monitored objects (TBMO) and prohibited behavior conditions indicating behaviors respectively prohibited to the TBMO in an area. Entry monitoring elements monitor as specific TBMO, TBMO which enter the area, and judge whether or not specific identification information identifying the specific to TBMO exists in the identification information stored in the storage element. When identification information coincident with the specific identification information exists in the identification information, behavior monitoring element monitor based on the specific identification information, the specific TBMO which behave in the area, and generate behavior information indicating behaviors of the specific TBMO. Behavior judging element select specific prohibited behavior conditions corresponding to the specific identification information from the plurality of prohibited behavior conditions stored in the storage element, and produce an alarm when behaviors indicated by the specific prohibited behavior conditions coincide with behaviors indicated by the behavior information.