To attain improvement in durability by suppressing occurrence of permanent distortion caused by residual stress of a resistance heating element by reducing frictional resistance between a support and the resistance heating element when thermally expanding/shrinking the resistance heating element.

A heat treatment furnace comprises: a tubular heat insulating material 4 surrounding a treatment container 3 for housing an object (w) to be treated therein and performing heat treatment thereon; a spiral resistance heating element 5 disposed along with an inner circumferential surface of the heat insulating material 4; a support 13 which is provided, along an axial direction, on the inner circumferential surface of the heat insulating material 4 and supports the resistance heating element 5 at a predetermined pitch; and a plurality of terminal plates 14 disposed at appropriate intervals in the axial direction outside the resistance heating element 5 and extended through the heat insulating material 4, in the direction of diameter, to the outside. In such a heat treatment furnace, the support 13 is formed in such a comb shape as to include a base 17 that is positioned inside the resistance heating element 5 and a plurality of supporting pieces 18 extending from the base 17 through the pitches of the resistance heating element 5 to the outside of the furnace in the direction of radius, and an upper surface of each of the supporting pieces 18 is formed in such a curved surface shape as to reduce frictional resistance when thermally expanding/shrinking and moving the resistance heating element 5.