System host (2) requests a command to local device (6), and local host (10) interprets the requested command and issues the command to local device (6). Local device (6) notifies local host (10) of an interrupt of command complete and local host (10) notifies system host (2) of the command complete. Data transfer between system host (2) and local device (6) is performed via advanced switching unit (8), and advanced switching unit (8) converts an address on local host (10) side into an address on system host (2) side and transfers PCI packets between local host (10) and system host (2).