To form a body covering lock(-hole) itself, to emit a warning sound when the body is detached from the lock(-hole), and to make a clue leave by a criminal when a status in which the warning sound is produced once, is brought while conducting control only by a resident.

A password switch with a contact controlling a relay and an alarm and a cover 30 covering the switch, a battery, etc., are installed into a body covering the lock(-hole) of a door(-knob). When the body is pulled up forcibly, an alarm is sounded, and a criminal is driven to the status in which only a means such as breakdown is used for stopping ringing or preventing ringing from the beginning, and a clue is made to leave.