PURPOSE: To provide an injection rate characteristic of long duration at the time of a low load and to provide an injection rate characteristic of rapid spill at the time of a high load.

CONSTITUTION: A cam 25 for cutting off to cut off fuel is provided separately from a cam 14 for oil delivery to deliver fuel in an inner cam type fuel injection pump, and cutting off speed of fuel is independently set by this cam 25 for cutting off. A characteristic to increase cam speed continuously in a force feeding process is given to this cam 25 for cutting off, cutting off speed is, decreased at the time of a low load where cutting off is fast, and the cutting off speed at the time of a high load where cutting off is slow is increased.