A control system for a throttle valve actuating device is disclosed. The throttle valve actuating device includes a throttle valve of an internal combustion engine and an actuator for actuating the throttle valve. At least one model parameter of a controlled object model which is obtained by modeling the throttle valve actuating device is calculated. A learning value of a throttle valve opening at which an actuating characteristic of the throttle valve changes, is calculated. The throttle valve actuating device is controlled using the learning value so that an opening of the throttle valve coincides with a target opening.