PURPOSE: Waste plastic solutions are sprayed into a fluidized gasification layer to remove the solvent and precipitate polymers, thereby separating waste plastic utilizing heat effieiently through simple processes containing dissolution and precipitation of waste plastics.

CONSTITUTION: After crashed in crashing process 12, waste plastics 11 are sent to dissolution process 13 where the plastics are dissolved in a solvent. The plastic solution is sent to desolvation process 16 of fluidized layer consisting of a fluidizing gas and recovered plastics and sprayed. The solvent of the sprayed solution of plastics evaporates with heat suppplied from the fulidized gas and the plastics precipitates on the surfaces of polymer particles and are recovered as product 7. Meanwhile, the fluidized gas containing the solvent is sent to dissolution process 13, where the solvent is recovered and the sensible heat of the solvent and fluidized gas is recovered as the heat for the dissolution.