PURPOSE: To eliminate a reference signal detection sensor by correcting the frequency of a specific reference signal according to increment/decrement of rotation of drive shaft, then controlling fuel injection timing according to phase difference between a corrected reference signal and a rotary phase signal.

CONSTITUTION: In a fuel injection pump 1, a plunger 6 inserted into a cylinder bore 5 is rotated through a drive shaft 7 and reciprocated through a face cam 8. A roller ring 3 is rotated through a timer piston 18 so as to regulate injection timing. A timing control valve 17 is controlled through a computer 20 based on a rotary phase signal fed from a pump angle sensor 22 fixed to the roller ring 3. Frequency of a specific reference signal is corrected according to increment/decrement of rotation of the drive shaft 7, and the injection timing is controlled according to phase difference between the corrected reference signal and the rotary phase signal.