PURPOSE: To facilitate the specification of a shoplifter by using a magnetizing body, degaussing a price adjusted commodity, and detecting magnetism from a stolen commodity which is not degaussed.

CONSTITUTION: A person to purchase the commodity having a magnetizing body 2 in a store goes out of the store from an exit gate 5 of the store in the condition without magnetic power after the magnetizing body 2 stuck to the commodity is degaussed by a degaussing device 4 provided on a counter 3 at the time of adjustment. On the other hand, a person to have the stolen commodity which is not degaussed at the counter 3 passes through the exist gate 5 in the condition in which the magnetizing body 2 generates magnetism as it is. A magnetic detecting sensor 6 provided on the exit gate 5 senses the magnetic force of the magnetizing body 2 of the stolen commodity, a transmitter 7 is operated in response to the output, and informs a guard, etc., by radio waves. The guard, etc., to receive the radio waves with a receiver 9 approaches the person to pass through the exist gate 5 then, can confirm the direction of the shoplifter having the stolen commodity out of persons to go out of the store, with the aid of a portable magnetic detecting sensor 10 and a magnetic direction indicator 11 held with them, and can identify him by approaching him further.