The contraction and deformation of a seal member are inhibited. To realize this, in a separator in which the shapes of projections and recesses forming at least fluid passages are inverted from each other on the front surface and the back surface of the separator and which is provided with a manifold for supplying and discharging a fluid, the separator, when a seal member for sealing the fluid is provided along the edge side of the separator forming the contour of the manifold, a projecting section capable of functioning as a spacer between the separator and another member adjacent to the separator is provided between the seal member and the edge side.