To provide a heat treatment device capable of suppressing leakage of a sublimate generated by cooling of a produced gas produced with a heat treatment of a heating object.

This heat treatment device 1 is so structured an air pipe arrangement 68 is arranged in a circulation system S composed of a heat treatment chamber 12, a hot air supply means 14 and ducts 17, 17. The air pipe arrangement 68 is arranged on the front side of the heat treatment device 1 by crossing a position adjacent to the down stream side in a flowing direction of a gas flowing in the heat treatment chamber 12. In an intermediate part of the air pipe arrangement 68, a heat exchange member 90 for facilitating heat exchange between the produced gas included in a gas flowing in the circulation system S and the air flowing in the air pipe arrangement 68 is mounted. The produced gas is cooled in the heat exchange member 90, and solidified and captured on the heat exchange member 90.