IDLING SPEED CONTROLLER OF INTERNAL COMBUSTION ENGINE, INTERNAL COMBUSTION ENGINE CONTROLLER AND INTERNAL COMBUSTION ENGINE

An idle rotational speed controller of an internal combustion engine includes an intake path 8 for sucking air supplied to a combustion chamber of the internal combustion engine 1, a throttle valve 11 arranged at the intake path 8 for controlling an intake amount, an auxiliary intake path 12 for communicating the intake path on an upstream side of the throttle valve 11 and the intake path on a downstream side or the throttle valve, and an opening/closing type control valve 13 arranged at the auxiliary intake path 12 for controlling an idling intake amount. Stable idling operation is carry out by including an intake pressure detecting unit S1 for detecting an intake pressure of the intake path 8, a fuel supplying unit for controlling a supply amount of a fuel supplied to the combustion chamber based on at least the intake pressure, and a controlling unit 15 for synchronizing a drive reference position for driving to open or close the control valve 13 with a timing of detecting the intake pressure by the intake pressure detecting unit S1.