Abstract: A process for classifying plastic-containing wastes which comprises dissolving a mixture of plastics containing polyolefin-type plastics in a hydrocarbon solvent (preferably of a xylene type) at a temperature of not lower than 60.degree. C. (preferably not lower than 80.degree. C.), vacuum-evaporating the solvent of the solution to cause precipitation of the polyolefin-type plastics dissolved therein, separating and recovering the major portion of the precipitate, further dividing the resulting separated solution into the concentrated liquor of the precipitate yet remaining admixed in the separated solution and the phase of a solution hardly containing the precipitate, recycling the concentrated liquor and using again for dissolving the mixture of plastics, and removing the solvent from the phase of a solution hardly containing the precipitate so as to recover the polystyrene-type plastics.