PURPOSE: To improve the responsiveness by detecting the output shown in the figure of an engine by an in-cylinder pressure sensor buried into a cylinder and controlling ignition timing so that the difference from a set aimed engine output becomes zero.

CONSTITUTION: The output shown in the figure of an engine is detected by the output value of an in-cylinder pressure sensor 6 for detecting the pressure in the combustion chamber of an engine 5. Further, an engine controller 9 calculates the ignition advance value corresponding to the ignition timing on the basis of the information supplied from the sensors such as throttle position sensor 3 and intake air quantity sensor 4 and the in-cylinder pressure sensor 6, and controls an ignitor 12. Therefore, even in the case when a load is applied sharply onto the engine in idling, the stable operation state can be maintained.