Two types of cation exchange membranes bearing sulfonic acid groups were prepared. One membrane (EA membrane), having episulfide groups beside sulfonic acid groups, was prepared with 2,3-epithiopropylmethacrylate (ETMA)-2-acrylamide-2-methylpropane sulfonic acid (AMPS) copolymers and the another one (EA-TTA membrane) having thiol groups, triethylenetetramine (TTA) side chains, and carboxyl groups beside sulfonic acid groups was prepared by treating EA membranes with TTA in a water-1,4-dioxane mixture solution. The transport of metal ions such as K+, Li+, Ag+, Ca2+, and Cu2+ through the membranes was investigated. The transport rate of Ag+ through the EA membranes was considerably lower than those of other metal ions from solution. High selective transport of Ag+ from mixed solution could be observed using the EA and EA-TTA membranes. Transport of Cu2+ and Ca2+ through the EA-TTA membrane was depressed by an electrostatic repulsion between ammonium groups in the membranes and metal ions when HNO3 or sodium ethylenediamine tetraacetate was used as receiving solution.