PURPOSE: To improve the abrasion strength and reduce the machining time by a method wherein mixed stock consisting in mixing molding stock with short fibers is press-molded into a predetermined shape and at least a part of the press-molded piece is polished so as to expose the short fibers.

CONSTITUTION: The molding stock such as synthetic rubber, plastics or the like and the short fiber cut in a certain fixed length are provided and mixed with each other at a certain fixed ratio. Next, the resultant mixed stock is extruded as it is by an extrusion molding machine and then cooled. The extrusion-molded piece contains fibers in the vicinity of its surface. Polishing is applied onto the area, in which the raised surface is formed. The polishing is performed by rotating a needled mat, a sand paper or the like. As a result of polishing, the molding stock layer in the surface area of the extrusion-molded piece is scraped so that the inner short fibers are protruded over the surface, changing the polished surface into raised state.