A polymer electrolyte fuel cell has an MEA-gasket assembly including an MEA having a polymer electrolyte membrane, a pair of catalyst layers, and a pair of gas diffusion electrodes, and a pair of gaskets provided on peripheral portions of surfaces on both sides of the MEA with gaps between the respectively adjacent gaskets and gas diffusion electrodes. A pair of electrically conductive separators is disposed to sandwich the MEA-gasket assembly with groove-shaped cell reaction gas passages on inner surfaces of the separators, each of the cell reaction gas passages running sequentially across a first portion of a respective gasket of the pair of gaskets, a first portion of a respective gap of the gaps, a respective gas diffusion electrode of the pair of gas diffusion electrodes, a second portion of the respective gap, and a second portion of the respective gasket. Each of the gaps is at least partially closed by a closure.