A fuel cell is provided which includes a catalyst layer to which hydrogen gas or air are introduced through both surfaces thereof a first separator disposed at a first side of the catalyst layer and including a plurality of first channels such that a first reactant among hydrogen gas or air flows; and a second separator disposed at the second side of the catalyst layer and including a plurality of second channels disposed in a direction perpendicular to the first channels. Particularly, each of the second channels includes a plurality of ventilation apertures such that a second reactant among the hydrogen and the air flows in a direction perpendicular to the second channels.