An electrode structure for a polymer electrolyte fuel cell comprises a pair of electrode catalyst layers and a polymer electrolyte membrane held between the electrode catalyst layers. The polymer electrolyte membrane is a sulfonation product of a polymer which comprises a main chain wherein two or more divalent aromatic residues are bound to one another directly or through oxy groups or divalent groups other than aromatic residues and side chains comprising aromatic groups to be sulfonated. The number of divalent aromatic residues comprised in the main chain of the above polymer is denoted by X, and the number of oxy groups comprised in the main chain of the above polymer is denoted by Y, and the value X/Y is within the range of from 2.0 to 9.0.