In a fuel cell stack, each separator is constructed by sequentially stacking and joining an anode-facing plate 42, a middle plate 43, and a cathode-facing plate 44. The anode-facing plate 42 has multiple hydrogen inlets 422i arranged in a two-dimensionally distributed manner on its plate surface. This arrangement effectively prevents a decrease of power generation capacity due to local accumulation of water produced in the course of electrochemical reaction for power generation or other impurities on the surface of either an anode or a cathode.