When an active data copy process relative to a logical storage device is performed without involving a computer, an access permission/rejection of the computer to the logical storage device is checked by referring to a correspondence between WWN of the computer and a logical storage device identifier LUN to thereby determine whether an access to a copy source logical storage device and a copy destination logical storage device is permitted or not. It is therefore possible to prevent an outflow of illegal data from a storage subsystem to be caused by an active copy instruction command.