Provided are a polymer electrolyte composition, an electrolyte membrane, a membrane electrolyte assembly, and a fuel cell. The polymer electrolyte composition according to an exemplary embodiment of this application includes a first solvent, a second solvent which is different from the first solvent, and a polymer which is reacted with the first solvent and the second solvent, in which the polymer includes a functional group which reacts with the first solvent by a first reaction energy and with the second solvent by a second reaction energy, and the second reaction energy is smaller than the first reaction energy.