PURPOSE: To simply and surely confirm safety for accident prevention and crime prevention by arranging a sensor for detecting whether a movable member exists or not on a position of the moving route of the movable member for the locking of doors or the main cock of gas.

CONSTITUTION: A door can be opened by rotating a handle 12 of a locking device 11 in the counterclockwise direction shown in a figure, and when a lock level 13 is rotated by 90° in the clockwise direction and horizontally laid, the door is locked and can not be opened even if the handle 12 is operated. A magnetic chip 14 is fitted to the rear side of the lock level 13 close to the chip, and when the lock lever 13 is laid to the horizontal state, the lock of the door can be detected even if a magnetic sensor 5 is driven. An output device 15 includes an electronic circuit for outputting an output signal of the magnetic sensor 15 as a radio signal e.g. together with a specific ID signal so as to response to a call signal applied from the external by means of radio waves or the like.