A fuel injection controller updates an air-fuel ratio learning value such that the amount of correction of a fuel injection amount according to an air-fuel ratio feedback correction value approaches zero. Further, the fuel injection controller makes an update rate of the air-fuel ratio learning value lower when the variation among respective-cylinder correction values, which are set for the respective cylinders in order to differentiate air-fuel ratios of a plurality of cylinders, is great than when the variation among the respective-cylinder correction values of the cylinders is small.