<p>A first arm member and a second arm member are provided. The first arm member is positioned between a cam and a valve body to oscillate in synchronism with the rotation of the cam. The second arm member changes the angle of the first arm member in accordance with the rotation angle of a control shaft. The temperature prevailing in the neighborhood of the control shaft and cam is detected. The rotation angle of the control shaft is corrected so as to avoid the influence of the detected temperature.</p>
