PURPOSE: To prevent a probable cause to stall an engine because an actuator comes into a lowest engine speed control position by action from a drive subject, by stopping idling engine speed feedback control when the engine is powered together with the drive subject transmitted.

CONSTITUTION: A deflection c between the output of an engine speed sensor 300 which detects a speed a of an engine 100 and a desired engine speed b is inputted to an arithmetic and logic unit 400. An idle switch 700 outputs a throttle valve desired position signal e when detecting a state of idling while a positional deflection f between the said position signal e and the output of a throttle position sensor 500 which detects an actual position d of a throttle valve 101 of the engine 100 is outputted to a driver 600 whereby feedback control for idling engine speed takes place. When a sensor swich 800 is connected to a car clutch as well as when a speed change gear is in a running position, operation of the arithmetic and logic unit 400 is stopped and feedback control is thus stopped.