INTERNAL COMBUSTION ENGINE CONTROLLER

The internal combustion engine controller includes an oxygen concentration sensor outputting an electric signal having a value depending on an oxygen concentration in an exhaust gas flowing through an exhaust passage of an internal combustion engine, and a control unit controlling fuel injection amount depending on at least the electric signal, the control unit being capable of performing atmospheric learning to calibrate the oxygen concentration sensor. The control unit is configured to perform the atmospheric learning when a changing rate of the value of the electric signal is lowered from above a predetermined threshold rate to below the predetermined threshold rate after a time of start of cutoff of fuel supply to the engine.