There may be provided a fuel cell stack unit comprising: a first gas separating plate; a first sealing gasket; a metal support, an end cell, and an air inlet being formed in the outer peripheral side of the center portion; a second sealing gasket; and a second gas separating plate stacked on the lower side of the second sealing gasket, wherein air introduced from the air inlet of the first gas separating plate successively passes through the air inlets formed in the first sealing gasket, the metal support, and the second sealing gasket, respectively, and flows from one side of the end cell to the other side thereof along a stacking boundary between the lower side of the end cell and the upper side of the second gas separating plate; and the second sealing gasket is recessed inward from an edge of the second sealing gasket.