A method for controlling the air-fuel ratio in an internal combustion engine in which the correction value of a transient fuel injection amount is decided, at a predetermined interval, in accordance with the acceleration or deceleration state of the engine, and the amount of fuel injection supplied to the engine is corrected by the decided correction value. In the process of the correction, the deviation of the air-fuel ratio from a reference air-fuel ratio in acceleration or deceleration of the engine is detected, and the correction value of the fuel injection amount correction in the transient state of the engine in accordance with the detected air-fuel ratio deviation is determined. In the correction of amount of fuel injection in the transient state of the engine, the correction value is decided on the basis of a factor for deciding the correction value and the blunted value of the factor for deciding the correction value.