Abstract text

A membrane-membrane reinforcing member assembly includes: a polymer electrolyte membrane (1) having a substantially square shape; a pair of membrane-like first membrane reinforcing members (10a) disposed on one main surface of the polymer electrolyte membrane (1) so as to extend along a pair of opposed sides, respectively, of four sides of said one main surface; and a pair of membrane-like second membrane reinforcing members (10b) disposed on another main surface of the polymer electrolyte membrane (1) so as to extend along a pair of opposed sides, respectively, of four sides of said another main surface, wherein: portions of the polymer electrolyte membrane (1) at which portions the first membrane reinforcing members (10a, 10a) and the second membrane reinforcing members (10b, 10b) are disposed are concave; and the first membrane reinforcing members (10a, 10a) and the second membrane reinforcing members (10b, 10b) are disposed such that main surfaces thereof are exposed, and the first membrane reinforcing members (10a, 10a) and the second membrane reinforcing members (10b, 10b) surround a peripheral portion of the polymer electrolyte membrane (1) as a whole.