There are provided an ion-exchange polymer including a structure represented by the following General Formula (1) and a production method therefor, an electrolyte membrane and a production method therefor, and a composition for producing an ion-exchange polymer. In a case where the sum of a1, b1, and c1 is 1.000, a1 is 0.000 to 0.750, b1 is 0.240 to 0.990, and c1 is 0.001 to 0.100. L represents an alkylene group, L1 and L2 each represent a divalent linking group, R1 is a hydrogen atom or an alkyl group, R2 and R3 each represent an alkyl group or an allyl group, X1− and X2− each represent an inorganic or organic anion, and Y represents a halogen atom. Z1 represents —O— or —NRa—, and Ra represents a hydrogen atom or an alkyl group.