PURPOSE: To precisely control the output torque of an engine always during speed change to surely prevent shock from being generated upon speed change, by estimating the range of variations in engine rotational speed, and by controlling the engine output torque in accordance with the thus estimated range so that the shock upon speed change is reduced.

CONSTITUTION: One control unit 1,000 is provided commonly to both engine and transmission. Output signals 220 to 224 are compensated in accordance with control factors, adjusting values thereof and time variation rates of the latter so that the output torque of the engine is controlled. Upon completion of speed change the rotational speed of the engine is estimated. This estimation can be made by multiplication with respect to the output rotational speed of a transmission unit upon completion of speed change. The kind of speed change is determined in accordance with the way of level change of either of the throttle opening degree obtained from an input signal 103 and input signals 142, 143, and the lowering amount of engine output is set in accordance with an estimated variation range of engine rotation speed.