With increasing demand for high fuel efficiency, better exhaust control measures, comfort and high performance on current vehicles, electronic control of the throttle chamber which decides the engine output, is getting advanced day by day. It is expected that this trend will be maintained towards electronic control of the throttle chamber in conjunction with injection air-amount control, drive control, traction control, etc. A control method for electronic throttle servo system is proposed, which consists of a DC motor, a throttle valve and a return spring. The control method fulfills the demand for high robustness in nonlinear opening of the throttle. In this paper, a sliding-mode controller with prescribed transient response is designed for electronic throttle chamber systems. By using a function augmented sliding hyperplane, it is guaranteed that the output tracking error converges to zero in a finite time. Simulation and experimental results are shown for the confirmation of effectiveness of the sliding-mode controller with prescribed transient response.