PURPOSE: To provide a titled treating furnace which makes baking uniform, and eliminates the need for controlling a large amount of wind quantity by heating a metallic strip while maintaining the catenary loci drawn by the metallic strip traveling in the furnace by a catenary system by means of floaters disposed along the catenary loci.

CONSTITUTION: Paint is coated on a metallic strip 4 by means of coaters 26 and 28 before and after a guiding roller 24. While the strip 4 is held afloat by upper and lower floaters 14, 16 during the time when the strip passes through a strip passage 18 of catenary curve shapes formed in a shell 6 through a shell inlet 20, the strip is dried in a drying zone 8. In a heating zone 10 and a polymn. reaction zone 12, the strip is subjected to baking. Thereafter the baked strip 4 is passed through an outlet 30 and is forcibly cooled by wind in a cooler 32, then the direction is changed by a guiding roller 34. The strip 4 is further cooled by the injection of water in a water cooling chamber 36 and after the strip is dewatered with wringer rolls 38, the strip is dried in a dryer 40, and is coiled as a product through guiding rollers 42, 44, 46.