An ion exchangeable mixture containing a polymeric compound consisting of an ion exchange resin, an acrylamide mixture containing at least one bisacrylamide and at least one acrylamide, and a copolymer obtained by reacting the polymeric compound with the acrylamide mixture, and a method of producing the same are provided. The ion exchangeable membrane produced by using the ion exchangeable mixture has significantly smaller electric resistance than conventional ion exchangeable membranes, and has excellent selective permeability because the ion exchangeable membrane is electrically charged. The ion exchangeable membrane can be produced under very mild production conditions, and thus can be produced very easily. Furthermore, the ion exchangeable membrane can be also formed into film during a crosslinking reaction in a solvent of water, and thus is advantageous in that the ion exchangeable membrane can be freely produced into desired sizes, shapes and forms.