The fiber channel switch is capable of protecting data even if communication for adjusting reserves of access rights, which is performed by communication means, is interrupted. The fiber channel switch comprises: a plurality of connection terminals connected to a host computer and a physical storage unit via fiber channels; a storage virtualization unit producing a virtual storage unit; a first communication unit for communicating with another fiber channel switch; an access adjusting unit for adjusting an access reserve between the fiber channel switches; a unit for setting a master-slave relation between the fiber channel switches; a block control unit for blocking access between the host computer and the physical storage unit via the fiber channel switch if the fiber channel switch is set as a slave when the communication between the fiber channel switches is interrupted.