NOVELTY - The cell has a unit cell with separators (18A, 18B) having gas cross grooves (18Ac, 18Bc) formed on convex ribs. Rear surfaces of the ribs constitute respective refrigerant passages (26a, 26b). An integral refrigerant passage has a cross sectional area that is equal to or larger than that of the passages (26a-b) and formed by combining two integral passages in a cell stacked direction when the separators are stacked. The separators are placed on either sides of a membrane electrode assembly (MEA).    USE - Used in a fuel cell vehicle.    ADVANTAGE - The grooves are formed on the convex rib of their separators such that even if one gas passage is blocked due to flooding occurring in a part of the separator surface, the gas can flow to an adjacent gas passage through the gas cross groove. Thus, it is possible to ensure the flow of the gas, and to avoid the situation in which electric power cannot be generated in the entire gas passage. The integral refrigerant passage has the cross sectional area equal to or larger than that of the refrigerant passages, and hence enables the integral refrigerant passage not to be divided by the gas cross groove, and the refrigerant can flow smoothly in the refrigerant passage. Therefore, both the gas and refrigerant can flow smoothly. The positions of the gas cross grooves deviates from each other in the direction in which the integral refrigerant passage extends, and hence it is not necessary to increase the depth of the refrigerant passages. Thus, it is not necessary to increase the thickness of the separators in order to allow the refrigerant to flow smoothly. Therefore, the size of the stack does not need to be increased in the cell stacked direction although the gas cross grooves are provided, and thus the stack is kept compact.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view showing a part of a unit cell to a separator passage structure of a fuel cell.    Membrane electrode assembly (MEA)    Separators (18A, 18B)    Refrigerant passages (26a, 26b)    Gas cross grooves (18Ac, 18Bc)    Concave grooves (18Ag, 18Bg)