Abstract: This invention provides a method for the manufacture of a fibrous plate rich in water resistance, which comprises the steps of uniformly mixing and dispersing fibrous raw material and finely divided bituminous substance in water, molding the resultant aqueous dispersion in the shape of a plate, and heating the plate with a hot press thereby melting the bituminous substance contained in the fibrous material and converting the plate into a fibrous plate having the bituminous substance uniformly dispersed therein. The fibrous plate obtained by this method excels in water resistance, weatherability, and thermal insulation and passes the standard specification concerning joint plates for use in concrete structures.