PURPOSE: To apply a uniform heat energy to all side surfaces of a molded member and provide a product having no warp at all by a method wherein one end of a long ceramic formed member heated from its surrounding part with a heater and the like is hung and it is rotated around the central axis in the vertical direction.

CONSTITUTION: A furnace tube 2 is held by a furnace tube guide 5 in a furnace body 4 and a heater 3 or the like are arranged around the furnace tube 2. An intermediate lid 8 where holes 8a of which the diameters are slightly larger than that of the molded member 1 and of which the number is the same as that of the furnaces is placed at an upper part of the furnace tube 2 so as to restrict an increase of convection heat and the upper lid 6 made of refractory board is arranged at the upper part of the furnace body 4 through the furnace tube guide 5. A molded member through-pass hole 6a is arranged at the same position as that of the intermediate lid 8 at the upper lid 6, and a guide pipe 7 is inserted into each of the holes. Then, each of the formed members 1 can be rotated around the central axis in a vertical direction under a rotation of chain 12 with a motor 10 of the rotating device arranged at the upper part of the upper lid 6, and heating the molded members 1 is made uniform.