A storage device, which is to be connected with hosts each having host-side communication ports and a multipath driver, includes logical storage units; communication ports; a driver type judging part that stores into a storage, when a prescribed SCSI command that a non-TPGS-compliant multipath driver does not transmit is received from a host by one of the communication ports, information indicating that the TPGS-compliant multipath driver is used in the host; and a command processing part, with respect to a SCSI command received via a communication path that is set as a standby path, judges by referring to the storage whether the TPGS compliant multipath driver is used in a host that transmitted the SCSI command, and, if the TPGS compliant multipath driver is not used in the host, processes the SCSI command assuming that the communication path is not the standby path.