An on-vehicle electronic control system has an input device for performing a plurality of manual input operations, wherein the input operations can be simultaneously and independently input; a processing device for independently processing the input operations and outputting respective processed results corresponding to the input operations; and a display device for independently showing the respective processed results. The display device may have a single display screen which is divided into a plurality of display sections for independently and simultaneously showing the respective processed results. The input device may have a microphone array including a plurality of microphones so as to simultaneously and independently perform a plurality of voice input operations. Typically, the input device assigns a task to any one of the input operations; and the processing device has a task content changing device for making the task be inherited and executed as a task assigned to another input operation.