Abstract: An ultra-high-temperature heat treatment apparatus includes an electric furnace, a furnace tube made of porous SiC/CVD-SiC, a heat-insulating apparatus fitted into the furnace tube for interrupting heat conduction from the furnace tube, a contamination control apparatus disposed beneath the furnace tube for preventing contamination in the furnace tube, and a separator mechanism for separating a wafer, subject to heat treatment in the furnace tube, from an annular holder. The electric furnace includes a heater comprised of heater elements which are replaceable independently of each other. Each heater element includes a heat-generating portion disposed along the inner wall face of the heat insulator so as not to be in close contact therewith, and a fixture portion fixed to the heat insulator. This heater construction makes it possible to reduce heater repair costs, suppress reactions between the heat-generating portions and the heat insulator, and suppress a contraction of the heat insulator.