There is provided a method for describing an ACPI machine language table used in a computer system having a multibridge PCI structure, which enables an OS to support hot plugs for PCI devices subordinate to a PCI multibridge. Upon receiving a call requesting a resource information method for a PCI device from an ACPI driver on an OS, a PCI configuration access is made to a subordinate bridge in a PCI device side, so that the ACPI machine language table supplied from a BIOS returns resource information of the PCI device. A PCI configuration access is made to a superordinate bridge in a PCI system bus side, to obtain resource information of the subordinate bridge. The resource information of the subordinate bridge is obtained from the superordinate bridge, and secondary resource information is obtained from a PCI configuration space of the subordinate bridge.