Abstract: A first link member (7), an upper-limit link member (9a), and a lower-limit link member (9b) are rotatably and axially coupled together. When the throttle is to be opened, the throttle valve (5) is electrically controlled by the motor (4) which has been under the control of an output from the accelerator opening sensing device (3), and at the same time, the throttle valve (5) is mechanically controlled by the wire (12) through the link members (7, 9a, 9b) in response to the degree of opening of the accelerator. A high degree of throttle operation such as traction control, idling control, constant speed run, etc. can be executed normally, and when an abnormality arises, the fail-safe function is at work to close the throttle valve (5).