To provide a heat treatment device capable of effectively utilizing the heat released from a treated object after heating treatment in a heat treatment chamber, by converting the heat into electric power in a cooling chamber.

The cooling chamber 2 is provided at a lower portion of the heat treatment chamber horizontally movably between a connecting position where an opening portion 21 is faced to a throat of the heat treatment chamber and a retracting position for opening a lower portion of the throat, and a thermoelectric conversion module is mounted on the whole surface of the cooling chamber including a lid body 22. The heat released from a heated semiconductor wafer W stored in the cooling chamber, is conducted to cooling water in a cooling jacket from a light absorbing body through the thermoelectric conversion module, and converted into electric power by the thermoelectric conversion module during this time.