A highly-reliable computer apparatus and path management method capable of reducing the impact of a failure in a physical I/O device on the entire virtual computer system is suggested.If a first path management unit detects a failure in a virtual HBA, it notifies a second path management unit of the failure; and in response to the failure notice, the second path management unit gives an instruction to the first path management unit corresponding to each virtual computer having another virtual HBA that uses a physical HBA corresponding to the virtual HBA in which the failure has been detected, to block the other virtual HBA; and if the first path management unit receives the instruction from the second path management unit to block the virtual HBA, it blocks the designated virtual HBA.