PURPOSE: To improve the heat resistance and durability of a friction material without detriment to its mechanical strengths by passing a friction material comprising a fibrous base material, a filler, a friction modifier, and a thermosetting resin and contg. a specific substance dispersed therein through water or hot water to remove the substance.

CONSTITUTION: A dispersion contg. a fibrous base material (e.g. natural pulp fibers or org. synthetic fibers), a filler (e.g. diatomaceous earth or a cashew resin), a friction modifier, and a sol. substance (e.g. granular, powdery, or fibrous PVA, vinyl acetate-maleic anhydride copolymer, polyvinyl methyl ether, water- sol. polyacrylic ester, polyacrylic acid salt, polyethylene oxide, etc.) is fed through a concn.-adjusting apparatus 21, a screen 22, and a flow box 23 to a wire gauge 27 to be formed into sheet, dehydrated in a pressing part 30 with presses 31-33. and dried with drying rolls 41, thus giving a friction material 8. The material 8 is passed through water or hot water to dissolve and remove the sol. substance to thereby form a porous structure.