A fuel cell separator and a fuel cell are provided that can improve uniformity in reaction gas flow rate and can prevent flooding due to excessive condensed water in passage grooves appropriately. A reaction gas passage region (101) of a separator (2) has a flow splitting region (21) having a passage groove group where the reaction gas is split, and one or more flow merge regions (22) having a recessed portion in which the reaction gas is mixed and connecting a plurality of flow splitting regions so that the passage groove group of the adjacent flow splitting regions (21) are connected to the recessed portion, and protrusions (27) vertically extend from a bottom face of the recessed portion and arranged in an island form. A pair of passage groove groups connected to the recessed portion of the flow merge region (22) is formed so as to have a greater number of grooves in the upstream passage groove group than the number of grooves of grooves in the downstream passage groove group. The recessed portion of the flow merge region (22) is defined, in a turn portion of a serpentine shaped reaction gas passage region (101), by oblique boundaries between the recessed portion and a pair of passage groove groups which are connected to the recessed portion and by the outer end of the turn portion.