To lustrously finish a comparatively hard metallic material with a high grade and with high efficiency by mixing a specific quantity of alumina balls to media for a dry barrel in mass.

Alumina balls of about 10 to 40 capacity % of media for a dry barrel are mixed in mass, and a work is polished while ventilating an air current in this mass. It is desirable that resinous media by solidifying fine abrasive grains by resin such as nylon, particularly, the ones by containing fine abrasive grains for a finish are adopted as the media for a dry barrel. Since the alumina balls are mixed in the mass, a projecting part of a comparatively rough work surface is efficiently polished and removed by the media for a dry barrel, and is crushed while being polished and removed small by the alumina balls. Therefore, when the work is comparatively hard metal, its comparatively rough surface is efficiently smoothed, and excellent luster is generated.