Provided are a system and related devices whereby it is easy to achieve I/O virtualization. A HUB device according to the present invention is provided with a switch for internal slots in a PC (for example, internal PCI-Express slots) and is configured to be able to interconnect internal slots in other PCs. In a computer system in which one or more PCs are interconnected by this HUB device, which serves as the central point of connection, each PC can “see” I/O devices of other PCs through the switch for the internal slots. Therefore, each PC creates a device list including I/O devices of the PC and I/O devices of other PCs, and the OS of the PC uses the device list. As a result, it is possible to easily achieve I/O virtualization.