A fuel cell stack including a plurality of electricity generation units fastened by means of a plurality of fastening members. Each electricity generation unit includes a single cell, and a sealing member sandwiched between two other members thereby sealing one of the anode chamber and the cathode chamber. The surface of the sealing member included in at least one electricity generation units, the surface facing either of the two other members, has a surface roughness Ra of 3.0 μm or less.