To insure that the organic components volatilized from ceramic shaped articles in a heat treatment process can be surely detected and that the exact heat treatment can be applied to the ceramic shaped articles and the rate of nondefective units can be improved by the results of the detection.

The heat treatment apparatus is provided with a first heat treatment space 3 for heat treating the ceramic shaped articles containing the organic components, a conversion section 4 for converting the carbon components included in a prescribed amount of the atmospheric gas taken out of the first heat treatment space 3 to a specific carbon compound, and a detection section 5 for detecting the component ratio of the specific carbon compound in the atmospheric gas.