An internal combustion engine control device comprising: an intake air quantity correcting device including: an intake air quantity obtaining means for obtaining an intake air quantity sensing value from an intake air quantity sensor that senses an intake air quantity flowing from an intake system into a combustion chamber of an internal combustion engine; an injection quantity obtaining means for obtaining an injection quantity sensing value from an injection quantity sensor that senses an injection quantity of fuel injected from an injector or a physical quantity relevant to the injection quantity; an oxygen concentration obtaining means for obtaining an oxygen concentration sensing value from an oxygen concentration sensor that senses an oxygen concentration in exhaust gas discharged from the internal combustion engine; a calculating means (S36, 31) for calculating a value of a sensing object to be sensed by a certain one of the intake air quantity sensor, the injection quantity sensor and the oxygen concentration sensor based on sensing values of the other two sensors; and an intake air quantity correcting means (S38, S40, 33) for correcting the intake air quantity sensing value based on a difference between the calculation value calculated by the calculating means (S36, 31) and the sensing value of the certain one of the sensors, the internal combustion engine control device being characterized by further comprising: an oxygen concentration calculating means for calculating an oxygen concentration in the exhaust gas based on the intake air quantity sensing value corrected by the intake air quantity correcting means (S38, S40, 33) and the injection quantity sensing value; and an exhaust gas recirculation controlling means for performing feedback control of an opening degree of an exhaust gas recirculation valve to approximate the oxygen concentration calculation value calculated by the oxygen concentration calculating means to a target value. an intake air quantity obtaining means for obtaining an intake air quantity sensing value from an intake air quantity sensor that senses an intake air quantity flowing from an intake system into a combustion chamber of an internal combustion engine; an injection quantity obtaining means for obtaining an injection quantity sensing value from an injection quantity sensor that senses an injection quantity of fuel injected from an injector or a physical quantity relevant to the injection quantity; an oxygen concentration obtaining means for obtaining an oxygen concentration sensing value from an oxygen concentration sensor that senses an oxygen concentration in exhaust gas discharged from the internal combustion engine; a calculating means (S36, 31) for calculating a value of a sensing object to be sensed by a certain one of the intake air quantity sensor, the injection quantity sensor and the oxygen concentration sensor based on sensing values of the other two sensors; and an intake air quantity correcting means (S38, S40, 33) for correcting the intake air quantity sensing value based on a difference between the calculation value calculated by the calculating means (S36, 31) and the sensing value of the certain one of the sensors, the internal combustion engine control device being characterized by further comprising: an oxygen concentration calculating means for calculating an oxygen concentration in the exhaust gas based on the intake air quantity sensing value corrected by the intake air quantity correcting means (S38, S40, 33) and the injection quantity sensing value; and an exhaust gas recirculation controlling means for performing feedback control of an opening degree of an exhaust gas recirculation valve to approximate the oxygen concentration calculation value calculated by the oxygen concentration calculating means to a target value. an oxygen concentration calculating means for calculating an oxygen concentration in the exhaust gas based on the intake air quantity sensing value corrected by the intake air quantity correcting means (S38, S40, 33) and the injection quantity sensing value; and an exhaust gas recirculation controlling means for performing feedback control of an opening degree of an exhaust gas recirculation valve to approximate the oxygen concentration calculation value calculated by the oxygen concentration calculating means to a target value.