PURPOSE: To widen the region of fuel injection control linearly by controlling the injection quantity of the fuel jetted from an injector not only from the injection time side but from the fuel pressure side for determining the injection quantity per time.
CONSTITUTION: A microcomputer 1 controls the valve opening time of an injector 2 according to the engine state. The fuel pressure P=Pf-PM is actually measured from the fuel feed pressure Pf and the intake pipe pressure PM, and compared with an aimed value Po, and if P>Po, a pressure control valve 4 is opened to return a portion of fuel into a tank 6 through a return pipe 5. If P<Po, the control valve 4 is left in closed state. When the aimed value Po is reduced, the correction operation for prolonging the injection time is carried out, and on the contrary, when the aimed value Po is increased, the correction operation for shortening the fuel injection time is carried out, and the switching of the aimed value is carried out so that the discontinuity of fuel injection quantity is not generated. the control region can be widened linearly by controlling the ON/OFF of the control valve 4 by the output of the microcomputer 1.