To solve the problem that metal is mixed into a crushed reusable plastic raw material due to incorrect checking of a metal part, especially an in-mold molded metal part, to hurt an apparatus when a plastic product is molded.

A crusher 1 for crushing a composite comprising a plastic material, a magnetic selector 2 for selecting metal attracted to a magnet from the crushed composite, a metal selector 3 for selecting metal unattracted to a magnet from the crushed composite, a vibrating mill 4 for separating lightweight foreign materials from the plastic material by scrubbing the surfaces of plastic pieces after metal selection, and a wind selector 5 for selecting the separated foreign materials are provided.