To provide a technique for more flattening desired portions of components mainly made of cemented carbide to be used for a tool material and a mold material.

In this component 10 polishing method, polishing is performed by using plastic selected from a group constituted of polybenzimidazoles, polycarbonates, polysulfones, polyethersulfones, polyarylates, polyamide-imides, polyetherimides, polyphenylene sulfides, polyetheretherketones, polyimides and polytetrafluoroethylenes, and the mixtures including copolymer.