To provide a crime prevention system capable of more certainly grasping the invasion of an unanticipated invader into a house, and notifying a resident who has come home.

This system is a crime prevention system in a house having a plurality of spaces and an entrance, and has human detection sensors 11a, 13a, 19a and an outdoor-side indication monitor 23b. The human detection sensors 11a, 13a, 19a are respectively installed in the space of a living room, and detect whether a person is present in the space or not. The outdoor-side indication monitor 23b can be visually recognized on the outdoor side of an entrance door 20, and performs indication based on detection results of the human detection sensors 11a, 13a, 19a.