PURPOSE: To suppress the dispersion of the pilot injection quantity and main injection quantity by carrying out pilot injection through the constant capacity feed under pressure by the extension of a piezoelectric element and carrying out only the main injection through the operation of a cam.

CONSTITUTION: A fuel injection quantity controller 28 carries out electric conduction to a piezoelectric element 30 during suction cycle, and the piezoelectric element 30 is extended and the hydraulic pressure in a pressure chamber 33 increases, and then, a valve piece 32 is urged to close a passage 37. Further, in the transition from suction to the discharge cycle, the voltage applied on the element 30 is increased furthermore. Accordingly, if the element 30 extends furthermore, and the hydraulic pressure in the chamber 33 increases over a prescribed value, an urged ball valve 36a opens a communication passage 35, and the fuel in the chamber 33 is introduced into a plunger chamber 20 through a communication passage 35, passage 37, overflow passage 18, spill port 27, and a fuel passage 24. Then, the pressure in the chamber 20 increases, and pilot injection is carried out. When the pilot injection is completed, main injection is started, and the electric conduction to the element 30 is stopped at the time point when a prescribed injection quantity is achieved, and main injection is completed.