PURPOSE: To smooth the speed of opening and closing a throttle valve in a car with torque converter, by changing said speed on the basis of the running condition of the car, when the valve opening is to be controlled in linkage with the amount of stamping-in on the accelerator pedal.

CONSTITUTION: Signals about the amount of stamping-in on the accelerator pedal 1 and the position of a shift selector lever 8 of a transmission 5 are entered in a throttle speed map 91, which constitutes a control part 90 for the throttle valve. The map 91 emits a signal, showing the optimum throttle opening/closing speed according to various parameters given, to a pulse motor 2 for adjustment of the throttle valve. At this time a counter 93 shows the revolving position of said pulse motor 2, and figures to show the number of pulses from the map 91 are accumulated. A comparator 92 judges the direction in which the throttle valve is controlled, and compares the value on said counter 93 with the target value of the degree of opening of throttle valve to be determined distinctly from the angle of stamping-in on the accelerator pedal.