Mapping tables are for stipulating information for primarily identifying computers, information for identifying a group of the computers and a logical unit number permitting access from the host computer inside storage subsystem, in accordance with arbitrary operation method by a user, and for giving them to host computer. The invention uses management table inside the storage subsystem and allocates logical units inside the storage subsystem to a host computer group arbitrarily grouped by a user in accordance with the desired form of operation of the user, can decide access approval/rejection to the logical unit inside the storage subsystem in the group unit and at the same time, can provide the security function capable of setting interface of connection in the group unit under single port of storage subsystem without changing existing processing, limitation and other functions of computer.