A throttle opening controller provided between an accelerator pedal and an engine throttle of an automobile. It has an output shaft driven by a motor, a motor lever fixedly mounted on the output shaft and ring members including an accelerator ring, a motor ring and a throttle ring all rotatably mounted on the output shaft. The accelerator ring is connected to the accelerator pedal and the throttle ring is connected to the throttle through wires. The motor lever is controlled by a traction control device. When the traction control is not activated, the motor lever is kept in its FULL-OPEN position, allowing the movement of the accelerator pedal to be transmitted as it is to the throttle through the accelerator ring, the motor ring coupled to the accelerator ring through a spring, and the throttle ring adapted to turn in the throttle-opening direction by and with the motor ring.