PURPOSE: To minimize the influence exerted on a system by halting system management at the time of diagnosing the generation of a self-fault and outputting a command instructing a stand-by service processor(SVP) to start system management.

CONSTITUTION: Each SVP previously selects a substitutive SVP to be a system SVP to be used when a fault occurs in the SVP itself from normal other SVPs. The SVP executes self-diagnosis by a self-diagnosis part 19, and when no fault occurs, continues a series of processing. If a fault occurs, a diagnostic interface 21 informs a fault processing executing part 15 of the occurance of the fault to halt system management and a substitutive SVP is recognized by referring to a substitutive system SVP management table and the substitutive system SVP is informed of a function substituting request through a transmission processing part 22.