A continuous polymerization apparatus is provided for producing an amphoteric electrolyte resin by continuous bulk polymerization at low cost, which apparatus includes a reaction vessel, the reaction vessel including at least four polymerization zones adjacent to each other in series, each polymerization zone being separated by a partition plate, the partition plates admitting a stirring shaft with stirrers, each of the polymerization zones having a thermosensor for sensing temperature within the polymerization zone, a heating device for heating the polymerization zone and a cooling device for cooling the polymerization zone.