PURPOSE: To provide optimum air-to-fuel ratio control in accordance with the warmed-up condition of an engine by correcting the fundamental amount of fuel supply with an incremental corrective value to be determined on the basis of the load and warmed-up condition of the engine, and thereby having a proper water temp. incremental correction of the fuel supply amount.

CONSTITUTION: During operation of an internal-combustion engine, an operator means 22 calculates the fundamental amount of fuel supply on the basis of output signals from a number of engine revolutions sensing device 20 and a suction air amount sensing device 21. Another operator means 25 calculates the incremental corrective value on the basis of output signals from a load sensing means 23, to determine the load from the degree of throttle valve opening, and a warmed-up condition sensing device 24 to determine the warmed-up condition of the engine from its coolant temp. A corrective fuel operator means 26 corrects the above-mentioned fundamental amount of fuel supply using said incremental corrective value and calculates thereby a corrected amount of fuel supply, and the fuel amount controlled according to this calculation through a fuel supply control device 27 is supplied to the combustion chamber.