PURPOSE: To effectually reduce the shock of acceleration and deceleration in a wide range of operation and prevent white smoke from being made, by gradually nearing the quantity of injected fuel or the degree of opening of an accelerator to an aimed value by every allowable alteration quantity in the acceleration or deceleration.

CONSTITUTION: It is detected by sensors whether the temperature of cooling water of engine, the speed of a vehicle, the shifted position of a manual transmission and the revolution speed of the engine are higher or lower than prescribed values. The maximum of allowable increases α1, α2, α3, α4, which are determined when said quantities are lower than the prescribed values, and the maximum of allowable decreases β1, β2, β3, β4, which are determined when said quantities are higher than the prescribed values, are used as a final allowable increase α and a final allowable decrease β. An aimed value Qi for the quantity of injected fuel is calculated depending on the revolution speed of the engine and the degree of opening of the accelerator. In the acceleration of the engine, the quantity of injected fuel is gradually augmented to the aimed value Qi by every allowable increase α. In the deceleration of the engine, the quantity of inected fuel is gradually reduced to the aimed value Qi by every allowable decreases β. The quantity of injected fuel is thus moderately controlled. This results in reducing the shock of the acceleration and deceleration and preventing white smoke from being made by the engine furnished with an intake orifice.