PURPOSE: To make it possible to protect a key from operation failures resultant from a malfunction assuming that a specific key is rightly returned although it is not returned yet, and prevent an illegal usage of a key.

CONSTITUTION: There is formed a plurality of key control member insertion units 15 which insert a plurality of key 30-mounted key control members 14 respectively. A plurality of lock devices 36 which lock and unlock the key control members 14 to be inserted into each of the key control member insertion units 15. A plurality of regulation members 42, which regulate the movement of a lock claw unit 35 of each lock device 36 from its locked position to its unlocked position, allows the lock claw units 35 of the lock devices 36 to move from their locked positions to their unlocked positions by the operation of an electric drive unit 8. A plurality of lock detection switches 55 detect that the lock claw unit 36 of each of the lock devices is placed in their respective positions. A control unit 60 connected to the lock detection switches 55 controls the electric drive unit 48, thereby controlling the unlocking operations of the lock claw units 35 of the lock devices 36.