In an electronic throttle control system, a target intake pipe pressure as well as a presumed value for the intake pipe pressure is calculated, so that a deviation between the target value and the presumed value for the intake pipe pressure is calculated. The deviation is compensated in an advancing side by an amount corresponding to a delay of response in the throttle control system. An intake air amount passing through a throttle valve is calculated based on the above compensated deviation and a presumed intake air amount. A target opening degree of a throttle valve is finally calculated based on the above-calculated intake air amount passing through a throttle valve. Accordingly, a response and stability of the throttle control can be improved.