To provide a continuously heat treating furnace in which an accurate temperature distribution can be controlled by using a gas combustion type radiant tube burner as a heating means of a heating chamber, and an adequate energy saving effect or an effect for reducing an amount of exhaust of CO2 can be obtained in the continuously heat treating furnace using a conventional electric heater as a heating means.

The continuously heat treating furnace comprises a plurality of heating chambers divided with respect to the conveying direction of a material 19 to be thermally treated, and conveying means 23 for conveying the material 19 to be thermally treated to adjacent heating chambers. In the heat treating furnace, at least one direction of the widthwise direction of each heating chamber and the lengthwise direction of the furnace is divided into a plurality of systems. In each system, the gas combustion type radiant tube burner 3 which has a surface facing the material 19 to be thermally treated as a heat generating surface 13 is disposed. The temperature of each gas combustion type radiant tube burner 3 can be independently controlled.