A fuel metering control system for an internal combustion engine having a plurality of cylinders. The system includes an air/fuel ratio sensor and engine operating condition detecting means for detecting engine operating conditions at least including engine speed and engine load. The basic quantity of fuel injection is determined by retrieving mapped data according to the engine speed and engine load. An adaptive controller is provided to calculate a first feedback correction coefficient to correct the quantity of basic fuel injection such that the detected air/fuel ratio is brought to a desired value, and second feedback loop is provided for calculating feedback correction coefficients to correct the quantity of fuel injection. The desired air/fuel ratio is corrected by a second air/fuel ratio installed downstream of a catalytic converter.