An information obtaining unit provided inside a system controller obtains operation states of processing units and processing units respectively of cabinets, calculates an average utilization of CPUs of the processing units, and determines whether or not any processing unit can be disconnected. When a hardware resource can be disconnected as a result of the determination, an electric power control determining unit calculates possible combinations of hardware resources to be disconnected and performs a disconnection by a cabinet unit when there is a combination enabling a disconnection by a cabinet unit.