A fuel injection controller (incorporated in an engine control ECU) for controlling an injection operation of an injector has a program for executing injections in plural injection patterns including an injection pattern of a multiple injection in a certain order into a certain cylinder of the engine during non-injection operation and a program for obtaining sums of fluctuation degrees of an engine operating condition due to all the injections in a first injection unit composed of one (single stage injection) of the plural patterns and all the injections in a second injection unit composed of a different one (multiple injection of two stages) of the plural patterns which are executed by the former program, with an injection condition (cylinder number and data number N).