A heat processing furnace comprises: a processing vessel for receiving an object to be processed by a heat process; a cylindrical heat insulation member surrounding the processing vessel; a helical heating resistor arranged along an inner peripheral surface of the heat insulation member; a support member for supporting the heating resistor. The support member includes a base part positioned on an inside of the heating resistor, and a plurality of support pieces extending radially outward from the base part through spaces between adjacent portions of the heating resistor so as to support the heating resistor, the support member being formed to have a comb-like shape. An upper surface part of each of the support pieces is formed to have a curved shape in order to reduce a frictional resistance generated when the heating resistor is moved upon a thermal expansion and a thermal shrinkage thereof.