Abstract: A heat-treatment apparatus having a combustion chamber (13), an apparatus main body (10) provided with said combustion chamber (13), a combustion burner (20) for supplying a heating gas to said combustion chamber (13), a flue for discharging a combustion gas generated in said combustion chamber (13) to the outside, and a heating vessel stored in said combustion chamber (13), said heating vessel (15) having a bottom and an opening on the top, said opening being opened and closed by a lid (16), and said heating vessel being provided with a communicating member (153) that is communicably open to the above said combustion chamber when said lid is closed. This heat-treatment apparatus can keep the emission gas generated during the treatment, and, waste valuable metals can be efficiently recovered, if contained.