To provide a heat treatment device capable of being utilized in drying and baking a coated surface of a workpiece, after drying and coating a surface to be coated, of the workpiece on which pretreatment such as washing is performed in a coating line.

This heat treatment device comprises a heat treatment furnace 40 opened at its lower side, a heating means (hot air circulation circuit 54, heating means 55, blower 56 for circulating hot air, and controller 57) in the heat treatment furnace 40, an opening/closing lifting body 45 for closing a lower release portion (opening portion 51) of the heat treatment furnace 40, a lifting driving means 44 for moving the opening/closing lifting body 45 up and down between an upper limit position for closing the lower release portion (opening portion 51) of the heat treatment furnace 40 and a lower limit position moved down to a lower part with respect to the heat treatment furnace 40 in parallel, and a workpiece supporting means 49 disposed on the opening/closing lifting body 45, and the workpiece W loaded on the workpiece supporting means 49 of the opening/closing lifting body 45 at the lower limit position, can be charged into the heat treatment furnace 40 by the moving-up of the opening/closing lifting body 45 to the upper limit position.