INTERNAL COMBUSTION ENGINE CONTROL DEVICE

To keep catalyst purification efficiency high and prevent deterioration of emission performance. Therefore, an internal combustion engine control device according to an aspect of the present invention includes: an oxygen storage ratio calculation unit that calculates an oxygen storage ratio of a catalyst based on a catalytic reaction model having at least a detection value of a first exhaust gas sensor disposed on an upstream side of the catalyst as an input; a statistical model calculation unit that predicts a catalyst downstream exhaust gas concentration using a statistical model having an oxygen storage ratio as an input and a catalyst downstream exhaust gas concentration as an output; and an air-fuel ratio correction amount calculation unit that calculates an air-fuel ratio correction amount of an air-fuel mixture of an internal combustion engine based on a future catalyst downstream exhaust gas concentration calculated by the statistical model calculation unit.