A heating section 20 having heating elements using carbon which generates heat when a high-frequency electric current is fed to a coil whose pitch can be adjusted as desired is arranged in a heating chamber 10. A cooling chamber 80 configured to cool metal is disposed below the heating chamber 10 in communication with the heating chamber 10 via a connection section 60. A water-cooled vertically movable shaft 90 which is capable of supporting the metal to be heat-treated and entering the heating chamber 10 is disposed so as to penetrate through the bottom portion of the cooling chamber 80. A gas introducing pipe 81 configured to introduce gas for cooling heated metal to be heat-treated supported by the water-cooled vertically movable shaft 90 and moved from the heating chamber 10 to the cooling chamber 80 is disposed in the cooling chamber 80.