Abstract: A device for protecting premises such as residences, the device comprising at least one human presence detection sensor, a processing device and reaction mechanisms. The processing unit comprises mechanisms for modifying the operation of the reaction mechanisms each time the human presence detection sensor is activated. The reaction mechanisms may be of a conventional type comprising essentially light or acoustic devices. The device comprises mechanisms for simulating a presence inside the premises, controlled by the processing unit to simulate a presence in the occupant's absence. These simulation mechanisms may include lighting of the various rooms in the protected premises and activation of a tape recorder to play back human voices.