PURPOSE: To increase the surface exposing rate of a bioactive body such as antigen or antibody by irradiating an ionizable radiation on a laminar composite material consisting of the bioactive body, polymerizable monolayer body and porous carrier to make a polymn. treatment then stripping the laminar composite material.

CONSTITUTION: A thin film-like porous body such as cellulosic woven fabric or synthetic fiber woven fabric is used as the porous carrier. The carrier formed by laminating such bodies in multiple layers is impregnated with a vinyl monomer soln. dissolved therein with the antibody or antigen to the extent of slightly coating the surface of the carrier with the liquid and the coating is subjected to radiation polymn. at a low temp. The operation to strip the superposed and polymerized laminar polymers to each sheet of the carriers is then made. The antibody of the high polymer film is exposed on the surface by such operation. The ionizing radiation for the radiation polymn. is irradiated at 0W100°C radiation temp. The surface exposing rate of the bioactive body is thereby increased.