A control apparatus of a throttle valve in an internal combustion engine having a manually operable accelerator pedal. The control apparatus comprises a spring biasing the throttle valve in the opening direction, a first operating mechanism including an accelerator link mechanically connected to the accelerator pedal and a second operating mechanism including an electric motor. The first and second operating mechanisms can operate the throttle valve against the spring and independently of each other, the first operating mechanism thereby defining an upper limit of the degree of opening of the throttle valve in a predetermined relationship with the degree of depression of the accelerator pedal, and the second operating mechanism defining the degree of opening of the throttle valve within that upper limit.