PERFLUOROPOLYMER, LIQUID COMPOSITION, POLYMER ELECTROLYTE MEMBRANE, MEMBRANE ELECTRODE ASSEMBLY AND POLYMER ELECTROLYTE WATER ELECTROLYZER

To provide a perfluoropolymer capable of producing an electrolyte membrane excellent in mechanical strength in high temperature environments; as well as a liquid composition, polymer electrolyte membrane, membrane electrode assembly and polymer electrolyte water electrolyzer, obtainable by using the perfluoropolymer. The perfluoropolymer of the present invention contains perfluoromonomer units, does not substantially contain units having a halogen atom other than a fluorine atom, does not substantially contain units having a ring structure, and has acid-type sulfonic acid groups, wherein the perfluoromonomer units contain at least one type of units A selected from the group consisting of perfluorovinyl ether units and perfluoroallyl ether units; the ion exchange capacity is from 0.9 to 1.4 milliequivalent/gram dry resin; and the storage modulus at 120° C. is at least 100 MPa.