Fuel cell stack

A fuel cell stack comprising:

• a plurality of fuel cells, each of the fuel cells including a membrane electrode assembly sandwiched between a pair of separators that have flow passages through which gas to be supplied to the membrane electrode assembly flows, the membrane electrode assembly comprising an electrolyte membrane sandwiched between a pair of electrodes, the pair of separators being arranged across the membrane electrode assembly such that the pair of separators contact the membrane electrode assembly on opposing sides thereof, and each separator of the pair of separators comprising bottom portions in contact with the membrane electrode assembly and protrusions that protrude from the bottom portions in a stacking direction of the fuel cell;
• and
• at least one welded portion where separators adjacent to one another in the stacking direction are welded, the at least one welded portion being formed between at least one pair of protrusions adjacent to one another in the stacking direction,
• wherein a height, in the stacking direction, of a protrusion of a given separator on which a welded portion is formed is less than a height, in the stacking direction, of a protrusion of the given separator on which a welded portion is not formed.