To provide a heat-treating furnace with which the heat-treatment of a metal to be heated such as aluminum alloy, is efficiently performed.

This furnace 21 has an upper and lower two step layer structure and the upper layer is used for hot-blast heat-treating furnace 3 and the lower layer is used for fluidized bed heat-treating furnace 5. An opening/closing door is arranged between the hot-blast heat-treating furnace 3 and the fluidized bed heat-treating furnace 5. In the case of performing the heat-treatment to the metal 19 to be heated, the metal 19 to be heated is heated up to a setting temperature in granular materials 12 of the fluidized bed heat-treating furnace 5, and after brushing off the granular material stuck to the metal 19 to be heated with air from high pressure air piping 11, the metal 19 to be heated is transferred into the hot-blast heat-treating furnace 3 by opening the opening/closing door and held to a setting temperature. The exhaust gas E1 of the fluidized bed heat-treating furnace 5, is utilized for the atmosphere in the hot-blast heat-treating furnace 3. Further, the exhaust gas E2 of the hot-blast heat-treating furnace 3 is heat-exchanged with the air A from a blower 17 as the new air of a burner 7-1 in the hot-blast heat-treating furnace 3 by using a heat-exchanger 15.