Provided is a heat treatment apparatus which can prevent attachment of powder to a heating part without additional steps and devices. In the heat treatment apparatus (1), mixture gas of condensable gas and powder (10) flows towards the heating part (4) at a flow rate of lower than 200m/second, and the powder (10) is heated with the condensable gas, wherein the inner peripheral surface of the heating part (4) is made of non-adhesive material, and a contact angle of the non-adhesive material and water is greater than 90 degrees. Therefore, the mold release properties and water repellence of the inner peripheral surface of the heating part (4) are improved, and attachment of the powder (10) caused by different specifications of the inner peripheral surface of the heating part (4) is prevented without additional steps and devices, so that the powder (10) is prevented from quality degradation and mixing of foreign material so as to prevent change of heat treatment conditions, operation interruption caused by blockage of the heating part (4) is prevented, and the heat treatment apparatus can work continuously.
