To provide a thermal cracking equipment of expanded polystyrene and non-expanded polystyrene in the same treatment facility efficiently and at a low cost.

This thermal cracking equipment comprises the steps of dissolving the expanded polystyrene in a solvent in a solution tank (1), feeding the solution to a tubular reactor type thermal cracking device (3) via a pipe (a) equipped with a throttling device (4), while heating and melting the non- expanded polystyrene in a melting device, feeding the molten polystyrene to the thermal cracking device (4) via a pipe (b) equipped with a throttling device (4). The throttling device (4) manages the polystyrene solution and the polystyrene melt to start or stop of feeding or to regulate their amounts of flows so that at least one of them is fed to the thermal cracking device (3) to be thermally cracked.