PURPOSE: To omit the use of the special hardware and to prevent the deterioration of throughput of a file access owing to the transfer of data carried out via another bus between hosts by adding a shared file to which the accesses are possible from both hosts onto an SCSI bus and attaining the access control.

CONSTITUTION: It is checked whether a file control table had a change or not every time both hosts 12a and 12b carry out the processes in accordance with the request contents received from a user application. If the file control table had a change, this table is written into another file control table stored in a shared file storing device 15. then the change of the control table is given to another host by means of a command of a small computer system interface. Receiving this information, the host reads a file control table out of the device 15 and updates its own file control table. As a result, the file access control is attained between the hosts without using any special hardware.