A control device of an internal combustion engine calculates on the basis of the air-fuel ratio difference a correction for the estimated fuel supply amount correction for correcting the estimated fuel supply amount to make the estimated and detected air-fuel ratios correspond to each other and calculates correction values for the fuel supply difference compensation and the air amount detection difference compensation by dividing the correction value for the estimated fuel supply amount correction, using the fuel supply and air amount detection difference proportions, and performing the air-fuel ratio control, using the corrected estimated fuel supply and detected air amounts. The correction value for the estimated fuel supply amount correction is divided to the correction values for the fuel supply difference compensation and the air amount detection difference compensation such that a value equivalent to the air-fuel ratio difference becomes equal to the air-fuel ratio difference, using these correction values.