PURPOSE: To reduce the input/output frequency and the access time in the reference/updating state of a program source file and to improve the reliability of the program source file by controlling the program source file which is generation controlled through a generation control storage area.

CONSTITUTION: A generation control storage area 3 is provided with a recording means which records the unsubstituted and substituted records when the generation control is applied to a program source file 5, a recording means which records the added records and the positions of these records, and a recording means which records the deleted records respectively. When a record reference/ updating request is received from a program file access requester 1, an access control part 2 refers to and updates a record control part 4 which stores each generation record included in the area 3. Then the part 2 has the reference/ updating accesses to the file 5 based on the information on the part 4.