TECHNOLOGY FOCUS - POLYMERS - Preferred Preparation: The polymerization is carried out in a concentration of 20 mg/ml to 10 g/ml of monomer (I), 10 mg/ml to 6 g/ml of monomer (II), 0.1 mg/ml to 2 g/ml of monomer (III), 20 mg/ml to 10 g/ml of monomer (IV).The polymerization is carried out with a hydrophobic polymerization initiator of 0.01-20 wt. % based on the total amount of monomer (I), monomer (II) and crosslinking agent (V) and with a hydrophilic polymerization initiator of 0.01-15 wt. % based on the total amount of monomer (II) and monomer (IV). An ion-exchanging film is prepared by casting ion exchanged resin solution having viscosity of 50-40,000 cps on a base material having a fixed area, and drying the resin solution at temperatures which have difference of within 20 degreesC between the highest temperature and the lowest temperature.Preferred structure: In (1), Monomer (I) is vinyl monomer, carboxyl type (II) is carboxyl group-containing vinyl monomer, the oriented type (III) is an oriented monomer, the strong acid type (IV) is a sulfonic acid group-having vinyl monomer and the crosslinking agent (V) is a divinyl crosslinking agent. Preferred Definitions:    R1, R2 and R5 = H or aliphatic chain;    R3, R4 = H or aliphatic chain-like styrene derivative;    R6 = aliphatic chain or acrylic acid derivative monomer which may not exist;    R7 = aliphatic or aromatic vinyl monomer having orienting ability by the integral effect of polymerization;    R8 = aliphatic or aromatic sulfonic acid;    R9 = spiro structure;    Most Preferred Definitions:    R1-R5 = H;    R6 = acrylic acid monomer which may not exist;    R7 = naphthalene ring;    R8 = amido-2-methylpropanesulfonic acid;    R9 = 2,4,8,10-tetraoxospiro(5,5)undecane.    EXAMPLE - A hydrophobic monomer solution was prepared by dissolving styrene (0.0966 mol), 2-vinylnaphthalene(0.00483 mol), 3,9-divinyl-2,4,8-tetraspiro(5,5)-undecane(0.00435 mol) and azobisisobutylonitrile (0.20 g) in N,N-dimethylformamide(11 ml). A water-soluble monomer solution was prepared by dissolving 2-acrylamide-2-methylpropanesulfonic acid (0.0483 mol) and acrylic acid (0.0966 mol) in water (4 ml) and ammonium peroxodisulfate (0.10 g). The water-soluble monomer solution was dropwise added to the hydrophobic monomer solution under stirring. The mixture was heated from room temperature to 80degreesC over 4 hours to give a viscous yellow polymer solution. The solution was adjusted to a viscosity of 3000 poise with N,N-dimethylformamide, passed through a glass filter and cast on a plate to give film. The film had an ion conductivity of 0.224 S/cm.