To provide a structure for fixing a holder for supporting an electric heater to a side wall of a furnace in which the holder for the electric heater can be positively fixed to the side wall of the furnace without being influenced by an atmosphere in the furnace and a thermal variation in the furnace or temperature fall or temperature rise at the time of stopping operation of the furnace.

There is provided a holder fixing structure in which a holder 13 for supporting a beltlike electric heater 12 is arranged a sidewall of a processing furnace having a refractory material lined inside. As the refractory material, blocks 11 having ceramic fibers with electrical insulating characteristic stacked up in their compressed state are used. A base section 20 of the holder 13 having at its extremity end some engaging sections 19 for mounting the electric heater 12 from above and holding it is buried at the block 11 in a non-contact state with the furnace iron surface outside the block 11. Further, the base section 20 of the holder 13 is provided with stopper mechanisms 21, 22 for holding the buried holder 13.