Abstract: An air-fuel ratio control method controls the air-fuel ratio of an air-fuel mixture supplied to an internal combustion engine having spark plugs, and heaters for heating the air-fuel mixture in the vicinity of respective ones of the heaters, the air-fuel mixture containing a fuel which is poor in atomizing characteristic at a low temperature. The method comprises the steps of (1) determining whether or not a temperature of the engine is lower than a predetermined value, (2) determining whether or not the engine is being cranked, (3) detecting an amount of electric current flowing through each of the heaters, and (4) controlling an amount of fuel supplied to the engine based on the detected amount of electric current when it is determined that the temperature of the engine is lower than the predetermined value and at the same time the engine is being cranked.