PURPOSE: To prevent occurrence of slippage and improve heat resistance and durability of an engine by feed-forward reduction controlling driving force independently on acceleration slippage of driving wheels according to a high load state.

CONSTITUTION: A second throttle valve 4 is not controlled while being in an opening state as indirected by a solid line in the case that a car runs straight, even when an engine 1 is determined to be in a high load condition. When a slippage rate is increased to exceed a specified value, afterward, the second throttle valve 4 is controlled according to the slippage rate. When the car is determined to be in a turning condition, an opening θ of the second throttle valve 4 is controlled so as to satisfy the following equation: θ=Acc×(1-α), where Acc is an accelerator opening, # is a coefficient that increases according to an engine load. Thus, slippage hardly occurs. When the slippage rate exceeds a specified value, the second throttle valve is controlled according to the slippage rate.