Disclosed is an air flow metering apparatus for an internal combustion engine of the type in which heating current supply to a hot-wire air flow meter (1) for detec­tion of engine suction air flow rate is made intermittent in synchronism with the rotation of the engine so as to directly generate a flow rate detection signal in the form of a pulse width signal. The apparatus comprises a computing means (20b) for generating a correction data by using variables including the rotation period of the engine and the opening rate of a suction air flow control means, whereby an air flow data obtained from the pulse width signal is corrected on the basis of the correction data.