PURPOSE: To produce an improved W/O emulsion polymer suppressed in the formation of agglomerates and improved in stability by emulsion-polymerizing acrylamide, acrylic acid and a cationized (meth)acrylic ester in a specified cyclic unsaturated hydrocarbon.

CONSTITUTION: At least one hydrophilic monomer selected from among acrylamide, acrylic acid and a cationized (meth)acrylic ester of the formula (wherein R is H or methyl; R1 to R3 are each methyl or ethyl; and (n) is 1 or 2) is dissolved in water in an amount about one to three times as large as the weight of the monomer to obtain an aqueous solution. This solution is added to an oil phase solution prepared by dissolving 0.1-15wt.%, based on the entire, emulsifier to a hydrophobic medium in an amount 0.4-1.5 times as large as the weight of the water and adding 0.1-5wt.%, based on the hydrophilic monomer, cyclic unsaturated hydrocarbon having at least one unsaturation in the ring to form an emulsion. This emulsion is subjected to a polymerization reaction for about 2-10hr at a pH of 3-10 and a temperature of 40-80°C in the presence of a polymerization initiator.