A control system for an internal combustion engine including a plurality of cylinders (#1 to #4), a plurality of exhaust passages (7c,...,7f) extending from the plurality of cylinders, respectively, and one exhaust passage into which the plurality of exhaust passages are combined, the control system controlling an amount of fuel to be supplied to the plurality of cylinders, on a cylinder-by-cylinder basis, thereby controlling an air-fuel ratio of exhaust gases emitted from the plurality of cylinders, the control system comprising: fuel amount-determining means for determining an amount of fuel to be supplied to each of the plurality of cylinders; air-fuel ratio parameter-detecting means for detecting an air-fuel ratio parameter indicative of an air-fuel ratio of exhaust gases in the one exhaust passage; simulation value-generating means for generating a plurality of simulation values simulating respective behaviors of air-fuel ratios of exhaust gases emitted from the plurality of cylinders; estimation means for estimating an estimation value of the air-fuel ratio parameter based on a model defining a relationship between the estimation value and the plurality of simulation values; identification means for identifying a plurality of model parameters of the model according to the detected air-fuel ratio parameter and the generated plurality of simulation values, such that the estimation value of the air-fuel ratio parameter becomes equal to the detected air-fuel ratio parameter; first correction value-calculating means for calculating a first correction value for correcting the amount of fuel to be supplied to the plurality of cylinders, according to the identified plurality of model parameters, on a cylinder-by-cylinder basis; and first fuel amount-correcting means for correcting the determined amount of fuel according to the calculated first correction value, on a cylinder-by-cylinder basis. fuel amount-determining means for determining an amount of fuel to be supplied to each of the plurality of cylinders; air-fuel ratio parameter-detecting means for detecting an air-fuel ratio parameter indicative of an air-fuel ratio of exhaust gases in the one exhaust passage; simulation value-generating means for generating a plurality of simulation values simulating respective behaviors of air-fuel ratios of exhaust gases emitted from the plurality of cylinders; estimation means for estimating an estimation value of the air-fuel ratio parameter based on a model defining a relationship between the estimation value and the plurality of simulation values; identification means for identifying a plurality of model parameters of the model according to the detected air-fuel ratio parameter and the generated plurality of simulation values, such that the estimation value of the air-fuel ratio parameter becomes equal to the detected air-fuel ratio parameter; first correction value-calculating means for calculating a first correction value for correcting the amount of fuel to be supplied to the plurality of cylinders, according to the identified plurality of model parameters, on a cylinder-by-cylinder basis; and first fuel amount-correcting means for correcting the determined amount of fuel according to the calculated first correction value, on a cylinder-by-cylinder basis.