A fuel cell separator of the present invention is a plate-shaped fuel cell separator including a reaction gas supply manifold hole 21, a reactant gas discharge manifold hole 22, a groove-shaped first reactant gas channel 131, and one or more groove-shaped second reaction gas channels 132 and 133, wherein the first reactant gas channel 131 includes a first portion 41 and a second portion 51 located upstream of the first portion 41, and a cross-sectional area of a first specified portion 81 which is a continuous portion including at least the first portion of the first reactant gas channel 131 and/or a cross-sectional area of a second specified portion 82 which extends continuously from at least a downstream end of the first reactant gas channel 131 is/are smaller than cross-sectional areas of the second reactant gas channels 132 and 133.