To provide an apparatus for treating waste plastics capable of choosing between the conversion of waste plastics into oils and the conversion into refuse derived fuels(RDF) in the treatment of waste plastics.

The apparatus for treating waste plastics are equipped with an extruder 33 and a melting vessel 34 which isolate chlorine by melting introduced waste plastics P; a decomposing vessel 36 which thermally decomposes waste plastics P to convert them into oils; RDF-forming equipment 35 for solidifying waste plastics P to convert them into refuse derived fuels; and a controller which selectively feeds the waste plastics P melted in the extruder 33 and the melting vessel 34 to the decomposing vessel 36 and the RDF-forming equipment 35.