Access control program for controlling a file system driver of an electronic computer (1,11,201) connected with a plurality of devices (6,15,16,27,34), including a storage device, and having an operating system for operating said electronic computer (1,11,201), the electronic computer (1,11,201) comprising the file system driver, wherein when access is made from an input device (15,27) of said electronic computer (1,11,201) or an application program to a specific file in a file system of said electronic computer (1,11,201), said access control program allows said electronic computer (1,11,201) to function as a means for controlling an access instruction requesting said access, wherein said access control program is provided for data transfer between different device drivers (5, 21, 24, 33, 40) and comprises: an interface means for receiving said access instruction; a flow control means controlling a flow of data by receiving said access instruction, obtaining said specific file and an access method by analyzing said access instruction, and transmitting said specific file and said access method to a data processing means, a referencing means for referencing an access control database comprising a column of filenames of a file in said file system and a column of at least one said access method defining a condition of said access for said file name of said file and for outputting a referencing result; said data processing means for receiving said specific file and said access method from said flow control means, for passing information concerning said specific file and said access method to said referencing means, for receiving said referencing result relative to said access method from said referencing means, for performing judgment whether said referencing result is normal, (VIII) for cancelling said access when the result of said judgment is abnormal, and for passing said access to a file system supervising driver means when the result of said judgment is normal; and said file system supervising driver means (a) for receiving said access from said data processing means, (b) for passing said access to said file system driver for controlling said file system, (c) for receiving a result of execution of said access from said file system driver and (d) for passing said result of execution to said flow control means; wherein said flow control means passes said result of execution to said interface means, wherein said interface means passes said result of execution to said input device (15, 27) or said application program, characterized in that said access control program is a common interface driver which is operated in the kernel mode that is an operating mode in which all instructions of said operating system are executable; wherein said access control program is located between a device driver layer and fundamental programs, said device driver layer including device drivers (5,21,24,33,40) for controlling said plurality of devices (6,15,16,27,34) respectively, and said fundamental programs being provided in the kernel mode by said operating system. an interface means for receiving said access instruction; a flow control means controlling a flow of data by receiving said access instruction, obtaining said specific file and an access method by analyzing said access instruction, and transmitting said specific file and said access method to a data processing means, a referencing means for referencing an access control database comprising a column of filenames of a file in said file system and a column of at least one said access method defining a condition of said access for said file name of said file and for outputting a referencing result; said data processing means for receiving said specific file and said access method from said flow control means, for passing information concerning said specific file and said access method to said referencing means, for receiving said referencing result relative to said access method from said referencing means, for performing judgment whether said referencing result is normal, (VIII) for cancelling said access when the result of said judgment is abnormal, and for passing said access to a file system supervising driver means when the result of said judgment is normal; and said file system supervising driver means (a) for receiving said access from said data processing means, (b) for passing said access to said file system driver for controlling said file system, (c) for receiving a result of execution of said access from said file system driver and (d) for passing said result of execution to said flow control means; wherein said flow control means passes said result of execution to said interface means, wherein said interface means passes said result of execution to said input device (15, 27) or said application program, characterized in that said access control program is a common interface driver which is operated in the kernel mode that is an operating mode in which all instructions of said operating system are executable; wherein said access control program is located between a device driver layer and fundamental programs, said device driver layer including device drivers (5,21,24,33,40) for controlling said plurality of devices (6,15,16,27,34) respectively, and said fundamental programs being provided in the kernel mode by said operating system.