PURPOSE: To restrain the generation of NOx effectively by a method wherein the combustion flame of a burner is produced as oxygen-excessive flame and fuel is fed into the combustion flame at a plurality of positions apart from the burner, in a regeneration/combustion switching system heating furnace, provided with a pair of burners having heat storage body to effect combustion and regeneration alternately.

CONSTITUTION: In a continuous heating furnace, a work 51 to be heated is heated by burners 1-8 and when combustion flame 56 is formed at the burners 1a, 2a side, exhaust gas is discharged out of opposing burners 1b, 2b to store waste heat into a heat storage body. In this case, a plurality of fuel feeding ports 11-15, 21-25 are provided at the upper and lower parts of the work 51 to be heated by a plurality of pieces per set of burner while the combustion flame 56 of respective burners is produced as oxygen-excessive flame and only fuel is fed through fuel feeding ports. When the burners 1a, 2a, for example, are burning, the fuel is thrown through the fuel feeding ports 13-15, 23-25, apart from the operating burners. According to this method, the rise of combustion gas temperature is restrained whereby the generation of NOx can be restrained.