The polymer electrolyte fuel cell of the present invention is equipped
with a cell having an MEA having a hydrogen ion-conducting polymer
electrolyte membrane and an anode and a cathode sandwiching the polymer
electrolyte membrane; a platelike anode-side separator positioned on one
side of the MEA so that the front surface thereof contacts the anode,
with fuel gas passages through which fuel gas flows being formed in the
front surface; and a platelike cathode-side separator positioned on the
other side of the MEA so that the front surface thereof contacts the
cathode, with oxidizing gas passages through which oxidizing gas flows
being formed in the front surface; a cell stack in which a plurality of
said cells is stacked; and a cooling water flow passage, through which
cooling water flows, formed on at least the rear surface of one from
among the anode-side separator and the cathode-side separator of at least
a prescribed cell in said cell stack; where said fuel gas, oxidizing gas,
and cooling water flow through said fuel gas passage, oxidizing gas
passage, and cooling water passage, respectively, in a manner not running
counter to gravity.