A power generation cell includes a membrane electrode assembly and first and second metal separators sandwiching the membrane electrode assembly. The first metal separator is a thin metal plate. A first seal member is formed integrally around the outer end of the first metal separator. A portion defining an orifice is provided in an outer marginal region of the first metal separator. The thickness H1 of the first seal member in the area covering the portion defining the orifice is larger than the thickness of the H2 of the first seal member in the area covering other portions.