A control apparatus for an internal combustion engine having a throttle valve disposed in an intake passage of said engine, and an evaporative fuel passage for supplying an evaporative fuel/air mixture to said intake passage, the evaporative fuel/air mixture being a mixture of air and evaporative fuel generated in a fuel tank for supplying fuel to said engine, said control apparatus being characterized by comprising: rotational speed detecting means for detecting a rotational speed of said engine; intake pressure detecting means for detecting an intake pressure of said engine; wide-open intake air amount calculating means for calculating a wide-open intake air amount according to the engine rotational speed, the wide-open intake air amount being an intake air amount corresponding to a state where said throttle valve is fully opened; theoretical intake air amount calculating means for calculating a theoretical intake air amount according to the wide-open intake air amount and the intake pressure, the theoretical intake air amount being an intake air amount corresponding to a state where no exhaust gas of said engine is recirculated to a combustion chamber of said engine; intake air amount detecting means for detecting an intake air amount of said engine; air-fuel ratio detecting means for detecting an air-fuel ratio in an exhaust passage of said engine; air-fuel ratio correction amount calculating means for calculating an air-fuel ratio correction amount according to the detected air-fuel ratio; learning value calculating means for calculating a learning value of the air-fuel ratio correction amount; reference intake air amount calculating means for calculating a reference intake air amount using the intake pressure, the engine rotational speed, the air-fuel ratio correction amount, and the learning value; lower limit value setting means for setting a lower limit value of the detected intake air amount according to the reference intake air amount; limit process means for performing a limit process for limiting the detected intake air amount within a range of values which are equal to or greater than the lower limit value; evaporative fuel/air mixture amount calculating means for calculating an amount of the evaporative fuel/air mixture supplied through said evaporative fuel passage to said intake passage; intake gas amount calculating means for calculating an intake gas amount by correcting the limit-processed intake air amount using the evaporative fuel/air mixture amount; and exhaust gas recirculation ratio calculating means for calculating an exhaust gas recirculation ratio using the theoretical intake air amount and the intake gas amount, wherein said engine is controlled using the exhaust gas recirculation ratio. rotational speed detecting means for detecting a rotational speed of said engine; intake pressure detecting means for detecting an intake pressure of said engine; wide-open intake air amount calculating means for calculating a wide-open intake air amount according to the engine rotational speed, the wide-open intake air amount being an intake air amount corresponding to a state where said throttle valve is fully opened; theoretical intake air amount calculating means for calculating a theoretical intake air amount according to the wide-open intake air amount and the intake pressure, the theoretical intake air amount being an intake air amount corresponding to a state where no exhaust gas of said engine is recirculated to a combustion chamber of said engine; intake air amount detecting means for detecting an intake air amount of said engine; air-fuel ratio detecting means for detecting an air-fuel ratio in an exhaust passage of said engine; air-fuel ratio correction amount calculating means for calculating an air-fuel ratio correction amount according to the detected air-fuel ratio; learning value calculating means for calculating a learning value of the air-fuel ratio correction amount; reference intake air amount calculating means for calculating a reference intake air amount using the intake pressure, the engine rotational speed, the air-fuel ratio correction amount, and the learning value; lower limit value setting means for setting a lower limit value of the detected intake air amount according to the reference intake air amount; limit process means for performing a limit process for limiting the detected intake air amount within a range of values which are equal to or greater than the lower limit value; evaporative fuel/air mixture amount calculating means for calculating an amount of the evaporative fuel/air mixture supplied through said evaporative fuel passage to said intake passage; intake gas amount calculating means for calculating an intake gas amount by correcting the limit-processed intake air amount using the evaporative fuel/air mixture amount; and exhaust gas recirculation ratio calculating means for calculating an exhaust gas recirculation ratio using the theoretical intake air amount and the intake gas amount, wherein said engine is controlled using the exhaust gas recirculation ratio.