PURPOSE: To improve productivity and reduce deterioration of mechanical physical property by a method wherein a coating film of a resin part supplied to an extruder is fined by a solvent, the resin is melted, the solvent is removed, and a kneaded matter of the resin and the fined film is extruded so as to regenerate the resin.

CONSTITUTION: A screw 11 of a twin-screw extruder is made by combining a full-flight screw element 12 and forwardly helical and inversely helical kneading disks 13, 14. A film decomposing section is formed in between the forwardly helical kneading disk 13 and the inversely helical kneading disk 14. A resin melting section is formed in the front of the inversely helical kneading disk 14. When a component produced by roughly crushing a coated resin component, for example, an automobile bumper is supplied, the film of the bumper is decomposed and fined by a solvent at the film decomposing section. The resin is melted at the resin melting section and the solvent is removed. Thereafter, a mixture of the resin and the fined film is extruded so as to regenerate the resin.