PURPOSE: To eliminate the need of installing CPU only for compulsory locking release and to prevent the occurrence of an economical problem by updating a system to an unlocking state when there is a request from locked CPU as against an unlocking request.

CONSTITUTION: The instruction operations of 'LOCK', 'UNLOCK' and 'WRITE' are executed by using a record control table 2, a register 3 and a record access control part 4. Only when prescribed time elapses from locking occurring time in locking information on the record control table 2 and when an unlocking instruction is received from CPU of a CPU number in locking information, the arbitrary locking instruction for the record from CPU can be received. Thus, the use of compulsory release means becomes unnecessary and an economically file access control system with high usability can be obtained.