PURPOSE: To improve secrecy and utilize the title system for discriminating the individual who performs locking, by registering the random signal, voice signal, etc., at the time point of locking into the memory device of a key and memorizing said signal into the memory part of the key.

CONSTITUTION: Locking is performed by a portable key 1, and the data such as random signal, voice signal, etc., at the time point is inputted. A signal generator 8 generates the signal corresponding to the data, and said signal is registered as key pattern into a memory device 5, and memorized into the memory part of the key 1 by a write-in device 6. When lock releasing operation is carried out by using the key 1, the key pattern is read out by a read-out device 2, and collation with the registered key pattern memorized in the memory device 5 is carried out by a comparator 7, and when accordance is judged, locking is released.