PURPOSE: To produce the title composite material which is excellent in water absorptivity and in which a highly water-absorptive polymer is fixed on the fibrous base in good stability, by applying a specified aqueous polymerizable monomer solution to a molded fibrous base, polymerizing the monomer and reacting the formed polymer with a crosslinking compound.

CONSTITUTION: 110,000pts.wt. aqueous solution containing a polymerization initiator and a polymerizable monomer based on acrylic acid at least 20% of which groups are neutralized with an alkali metal salt or an ammonium salt is sprayed onto 100pts.wt. fibrous base molded from a cellulosic fiber and/or a polyester fiber so that the diameter of polymer particles in the fibrous base may be 30W500μm, and 80W95wt% of the monomer is polymerized by heating to form a composite of a polymer is polymerized by heating to form a composite of a polymer obtained from the polymerizable monomer with the fibrous base. To this composite 0.01W10wt% (based on the polymer), crosslinking compound having at least two functional groups reactive with the carboxyl groups and/or the carboxylate groups, is added, and are reacted together at 50W200°C for several sec W 5hr.