PURPOSE: To improve precision of fuel injection amount in a fuel injection controller of an internal combustion engine suitable for the fuel injection device of a diesel engine.

CONSTITUTION: A fuel injection pump 1 for forcibly feeding fuel by a plunger 12 to reciprocate in synchronization with the operation of an internal combustion engine, and a timer device 26 for changing the relationship between the reciprocating operation of the plunger 12 and the crank angle are provided. A spark- advancing state of the plunger 12 operation is detected on the basis of the detected value of a rotational number sensor 35 for detecting the rotational angle of the cam plate 8 to which the plunger 12 is fixed and the detected value of a crank angle sensor. The prestroke to be applied to the plunger 12 is shortened and corrected as the spark-advance change amount per unit time is large, and the timing when a valve closing command is issued to an electromagnetic spill valve 23 is advanced, so as to start fuel injection.