To provide an apparatus and a method for efficiently distilling a polystyrene gel, recovering a solvent contained in a polystyrene gel, efficiently thermally decomposing the polystyrene, recovering a thermal decomposition oil, efficiently distilling the polystyrene gel, recovering the solvent contained in the polystyrene gel and recovering the polystyrene.

The apparatus for treating the polystyrene gel is equipped with a distillation and decomposition vessel, a condenser, a reboiler, a gas heater, a first liquid vessel and a second liquid vessel and making the distillation and decomposition vessel, condenser, reboiler, gas heater, first liquid vessel and second liquid vessel communicate in a prescribed order. The gas heater heats the solvent vapor of the polystyrene gel to a temperature not lower than the boiling point of the solvent and heats the vapor of the thermal decomposition oil of the polystyrene to a temperature not lower than the boiling point of the vapor of the thermal decomposition oil of the polystyrene. The solvent vapor of the polystyrene gel heated to the temperature not lower than the boiling point or the vapor of the thermal decomposition oil of the polystyrene heated to the temperature not lower than the boiling point enters the distillation and decomposition vessel.