PURPOSE: To prevent forgetting of the operation of a crime prevention device and simplify the use of it by providing a circuit for producing alarms when a person forgets how to operate the crime prevention device.

CONSTITUTION: A finger pushbutton type non-lock warning starting switch SW1 is provided to the strike part of a lock. A locking switch SW2 for outputting locking information when a dead-bolt is locked, is then provided. When a person goes out, the switch SW1 is switched on to output the warning information from a warning information detection means U. Then, the switch SW2 is switched on to output locking information from a locking start- information detection means V and to co-operate a warning start-switch non- turning-on detection means W, a memory means X, and a power supply circuit opening and closing means Y to turn the power supply on in a crime prevention device. Further, when a person forgets to push the switch SW1, an alarm BZ sounds by means of a means W. Conventional locks can thus be used and easily and positively operated.