The present disclosure relates to antioxidant for a polymer electrolyte membrane fuel cell electrode catalyst, which includes cerium hydrogen phosphate (HCe2(PO4)3(H2O)) in the form of a nanofiber, and an electrode and a membrane-electrode assembly including the same. The electrode for a polymer electrolyte membrane fuel cell of the present disclosure, wherein the antioxidant is dispersed, can improve the mechanical strength of an electrode catalyst layer and can minimize deterioration of chemical durability even after long-term operation. And, a fuel cell including the same can exhibit high output performance and can operate stably even after long-term operation.