PURPOSE: To efficiently control the access control information of a data set by providing each storage volume with an area for a data set protection control book.

CONSTITUTION: Each storage volume 25 is provided with the area for data set protection control, and the access control information for the data sets 12W14, etc., stored in each storage volume 25 is registered in the data set protection control books 22, 23 or 24 placed in the same storage volume as these data sets area placed. Accordingly, even for the data set 12 to be shared by ≥two systems, if the renewal of the protection control book due to the new generation or the deletion of the data set or the change of a pass word is performed by one system, the renewal comes automatically effective for all the systems.