1. An information processing apparatus, comprising: an overall control unit including: a main control unit which executes a main process for controlling said apparatus in a unified manner; and a plurality of sub-control units, including at least one sub-control unit which executes a task assigned by the main control unit during the execution of the main process, as a sub-process; and an interrupt unit including: an event detector which detects an event occurrence upon which an interrupt task is executed during the execution of the main process; and an interrupt notification unit which notifies said overall control unit of interrupt information indicative of the interrupt task according to the detected event, wherein the interrupt notification unit selects the sub-control unit, which is in a state capable of executing the interrupt task, from among the plurality of sub-control units, and notifies the selected sub-control unit of the interrupt information, wherein the sub-control unit notified of the interrupt information executes the interrupt task specified by the interrupt information, as a sub-process, and wherein interrupt processing in the information processing apparatus, from the event detection through completion of the execution of the specified interrupt task by the sub-control unit, occurs without activity by the main control unit in connection with the interrupt processing.