In a fuel cell, an elastic body provides first protrusion T10 that encompasses the perimeter of the passage hole at plate member 40 and the leading edge of which spans the entire region and tightly adheres to plate member 40, provides second protrusion S20 that is disposed within the placement region of reaction membrane 10 so as to encompass the perimeter of the gas diffusion layer, and provides third protrusion S30 that is disposed to encompass the region at which first protrusion T10 is disposed and the region at which second protrusion S20 is disposed, and is disposed outside the placement region for the reaction membrane, and the leading edge of which spans the entire region and tightly adheres to a separator 30.