A system for controlling fuel metering for a multi-cylinder internal combustion engine. In the system, a feedback loop having an adaptive controller and an adaptation mechanism coupled to the adaptive controller for estimating controller parameters .theta. is provided. The adaptive controller calculates a feedback correction coefficient using internal variables including the controller parameters .theta., to correct a quantity of fuel injection obtained by retrieving mapped data by engine speed and engine load, to bring a detected air/fuel ratio to a desired air/fuel ratio. The internal variables of the adaptive controller are set such that the feedback correction coefficient is 1.0 or thereabout, when the engine operation has shifted from an open-loop control region to the feedback control region.