PURPOSE: To detect events at high speed by providing a transient detection circuit and an event processor in addition to a control and arithmetic processor, and detecting the occurence of an event independently of the period of arithmetic of the control and arithmetic processor.

CONSTITUTION: An event processor 1 detects which event has occured according to signals SI input from sensors of various kinds. The event processor 1 anticipates events and transients which are very likely to occur using an event anticipating means 3. The order of judgment of events and transients is changed by a judgment order changing means 4 according to the result of this anticipation in such a manner that events with high probability are high in the order of precedence. If some event occurs, a control and arithmetic processor 2 performs arithmetic of a control program corresponding to the result of detection by the event processor 1, thereby outputting an output signal SO required at an event.