PURPOSE: To secure the running stability of a car, by finding desired throttle opening or desired boost pressure in each of plural engines, and performing feedback control with each signal out of a throttle valve opening sensor or a boost pressure sensor installed in each engine.

CONSTITUTION: An accelerator pedal operated variable to be detected by an accelerator pedal position sensor 6 is inputted into an engine control unit 7, and desired throttle valve opening or desired boost pressure in each engine 1 is found out of the specified calculating formula or the map stored in a memory. Next, a signal corresponding to a deviation with each feedback signal out of a throttle valve opening sensor or a boost pressure sensor being installed in each engine is outputted to an actuator 8, whereby the throttle valve opening is controlled so as to cause each engine output to be equalized. With this constitution, uniform driving force is transmitted to both front and rear wheels 3a and 3b, thus car running is stabilized.