PURPOSE: To improve reliability by a method wherein arrangement of selected and registered numberals and characters is compared with arrangement of preregistered numberals and characters, and when the two arrangements are equal to equal other, locking or unlocking is effected.

CONSTITUTION: When a numeral and character selecting key B is pressed, numberals and characters are displayed, in order, on a character display part A by means of a character generating circuit D. When the key B is released from pressing, necessary numberals and characters are selected. When a numberal and character registering key C is pressed, selected numberal and characters are inputted to an arrangement producing circuit F. Through repeti tion of similar operation, necessary arrangement is registered. Arrangement registered on the circuit F is compared with arrangement registered at a registering circuit G for arrangement for identification by an arrangement comparing circuit H to decide a result. When two arrangements are equal to each other, an unlocking device J is driven by means of an external control circuit I for unlocking.