To generate an alarm prior to the intrusion without permission into a house by another person on the basis of a signal obtained by spectrally analyzing specific vibrations generated according to a picking operation for notify neighboring areas.

This device comprises a sensor part 1 for detecting vibrations generated according to unlocking operation; a wave detector/delay circuit 3 for holding the vibration pulse, obtained by detecting the output of the sensor part 1 for a fixed time; and a counting timer 4 which is set at the generation timing of the output from the wave detector/delay circuit 3 and is reset after a prescribed time. When the output of the wave detector/delay circuit 3 is continued, exceeding the prescribed time counted by the counting timer 4, an alarm time setting timer 5 actuates the alarm 7 within a set time.