To provide a heat treatment apparatus for a carbon fiber, capable of preventing such a situation as to deteriorate quality of a product and having excellent mass productivity.

This heat treatment apparatus for the carbon fiber has a furnace body which composes such a flow channel as to allow a flow of the carbon fiber produced from a transition metal as a catalyst and a carbon source by its own weight and conducts heat treatment of the carbon fiber by heating the carbon fiber in the flow channel, wherein the heat treatment apparatus is equipped with a high-temperature part which is positioned in the furnace body and kept at a temperature higher than a boiling point of the transition metal when the heat treatment is conducted, a low-temperature part which is positioned in the furnace body and kept at a temperature lower than a melting point of the transition metal when the heat treatment is conducted, and a heating means for heating the low-temperature part up to a temperature higher than the melting point of the transition metal.