To provide a thermal decomposition apparatus which can supply a useful oily or gaseous fuel by thermally decomposing a polymer waste, such as a plastic waste, while minimizing friction loss without decreasing the rate of hot air flow.

This apparatus comprises a supply section capable of supplying a polymer waste, a first chamber having a melting section 104 for melting the polymer waste supplied, and a second chamber having a decomposition section 105. In each of the first and second chambers, a transfer pipe 118 in a cylindrical shape and a transfer screw 119 arranged rotatably in the transfer pipe are installed. For maximizing the heat transfer efficiency of hot air supplied into a space between the chamber and the transfer pipe, a screw-type heat transfer pin 138 is installed on the outer surface of the transfer screw. In the transfer screw, an auxiliary heating pipe is arranged and hot air is supplied into a space between the inner surface of the transfer screw and the auxiliary heating pipe.