PURPOSE: To specify an easy and convenient form by considering motion quantity of a plunger based on angular rotation of a cam.

CONSTITUTION: A indicates appearance of a preceding side surface of a cam lobe, and this is the preceding side surface to generate inward motion of a plunger 19. B indicates motion quantity of the plunger 19 considered based on a rotation degree of a cam 22A, and C indicates acceleration of the plunger 19. The plunger 19 has a period in which it moves at constant quantity in the period of the curve B, and supply of fuel is performed in this period. Subsequent to initial inward motion of the plunger 19, a first period B1 in which the plunger 19 moves at constant quantity is provided, a second period B2 in which plunger speed is increased is then provided, and a third period B3 in which plunger speed is reduced as a top part of the cam lobe gets closer is subsequently generated. The cam 22A has, therefore, parts corresponding to the periods B1-B2.