An even-driven interrupt processing is efficiently carried out in a multiprocessor system. A main control unit 112 executes a main process as a processing for controlling an apparatus in a unified manner. A sub-control unit 116 executes a task assigned by the main control unit 112 during the execution of the main process, as a sub-process. An event detector 162 detects an event occurrence upon which an interrupt task is to be preferentially executed during the execution of the main process. An interrupt notification unit 164 notifies the sub-control unit 116 of interrupt information indicative of an interrupt task in response to the detected event. The sub-control unit 116 notified of the interrupt information executes the interrupt task specified by the interrupt information, as a sub-process.