Proton conducting membrane

摘要

(Object) A proton conductive membrane capable of sufficient proton conductivity even at low humidities and low temperatures is provided. (Means for Solution) The proton conductive membrane includes a copolymer including an ion conductive polymer segment (A) and an ion nonconductive polymer segment (B), the membrane absorbing water when it is soaked in 90° C. water for 30 minutes of which the quantity of water showing freezing temperatures in the range of -30 to 0° C. is 0.01 to 3.0 g based on 1 g of the copolymer. The copolymer has a structure in which main chain skeletons of the copolymer are covalently bound at aromatic rings thereof through binding groups.