PURPOSE: To prevent the overrich of air-fuel ratio by supplying to an injector an acceleration pulse control signal in a case where the rotational speed of an engine is in a predetermined range based on the lapse of the engine rotational speed upon starting of the acceleration, and supplying to the injector a control signal based on the computed value when the rotational speed of the engine is out of the range.

CONSTITUTION: A fuel injection quantity control circuit 14 takes in the running condition of an engine, and computes a necessary fuel quantity to supply a control signal to an injector 20. In the control circuit 14, when the rotational speed of the engine is in a predetermined range after starting of the acceleration based on the lapse of the engine rotational speed at a point in time when the acceleration is started, an acceleration pulse control signal is supplied to each injector 20 and also when it is out of the range a control signal based on the computed value to each injector 20. In this manner, it is possible to prevent the overrich of the air-fuel ratio and to improve the fuel cost.