Abstract: An ion exchange membrane includes a layer S including a fluorine-containing polymer having a sulfonic acid group, a layer C including a fluorine-containing polymer having a carboxylic acid group, and a plurality of strengthening materials arranged inside the layer S and functioning as at least one of reinforcement yarn and sacrifice yarn. A and B satisfy following formulas: B?240 ?m??(1) 2.0?B/A?5.0??(2) wherein, when the ion exchange membrane is viewed from the top surface, A represents an average cross-sectional thickness of the membrane measured in pure water for a region, in which the strengthening materials do not exist, and B represents an average cross-sectional thickness of the membrane measured in pure water for a region, in which strands of the reinforcement yarn overlap with each other, and in a region, in which the reinforcement yarn overlaps with the sacrifice yarn.

Abstract: An ion exchange membrane includes a layer S including a fluorine-containing polymer having a sulfonic acid group, a layer C including a fluorine-containing polymer having a carboxylic acid group, and a plurality of strengthening materials arranged inside the layer S and functioning as at least one of reinforcement yarn and sacrifice yarn. A and B satisfy following formulas: B?240 ?m??(1) 2.0?B/A?5.0??(2) wherein, when the ion exchange membrane is viewed from the top surface, A represents an average cross-sectional thickness of the membrane measured in pure water for a region, in which the strengthening materials do not exist, and B represents an average cross-sectional thickness of the membrane measured in pure water for a region, in which strands of the reinforcement yarn overlap with each other, and in a region, in which the reinforcement yarn overlaps with the sacrifice yarn.