A fuel injection controller of an internal combustion engine decreases a target intake quantity stepwise and increases an opening degree command value of an EGR valve stepwise when the controller switches control to rich combustion control. Accordingly, an intake quantity gradually decreases and an EGR quantity gradually increases, so an oxygen quantity flowing into a combustion chamber (cylinder inflow oxygen quantity) gradually decreases. The injection quantity is gradually increased in accordance with the gradual decrease of the oxygen quantity. Thus, the fuel injection controller can perform processing for making an air fuel ratio rich in order to discharge nitrogen oxides from an occlusion agent while appropriately inhibiting torque fluctuation.