[en] By the development of synthesized functional membranes, the application research on membrane separation technology such as electrodialysis, pressurized dialysis and concentration dialysis is actively advanced, and the development of higher functional membranes has been desired. Radiation-induced graft polymerization is the excellent method for giving hydrophilic radicals and ion exchange radicals without impairing the characteristics of existing materials. In the development of separation functional membranes, the selection of the structure and characteristics of sensual radicals, the distribution of sensual radicals in membrane cross section and the shape of membranes is the important subject. As the radiation sources suitable to graft polymerization, Co-60 gamma ray sources and electron beam sources have been widely utilized industrially. The features of radiation-induced graft polymerization are shown. The synthesis of ion exchange resin and the application of ion exchange membranes are explained. Microfiltration membranes with minute holes have been used for separating colloid, bacteria and other fine particles as hollow thread module. The separation of metallic ions and proteins is reported. (K.I.)