A fuel cell in which a plurality of fuel-cell unit cells are stacked adjoiningly each other, each fuel-cell unit cell having a membrane electrode assembly sandwiched between a first separator and a second separator, wherein each of the fuel-cell unit including a fuel cell separator assembled to a membrane electrode assembly and having a first surface and a second surface as a back surface of the first surface as the first separator, the fuel cell separator comprising: a central region opposed to a power generation-enabled region of the membrane electrode assembly; a planar-shaped outer edge portion extending from the central region to outer edge of the central region; a first surface-side recessed groove part formed in the central region on the first surface; and a second surface-side recessed groove part formed in the central region on the second surface, wherein: grooves of the first surface-side recessed groove part and grooves of the second surface-side recessed groove part are located alternately on the first surface and the second surface in the central region by formation of a plurality of pit-and-bump stripes by press molding on the central region, the outer edge portion is joined to a site outside the power generation region of the membrane electrode assembly, and a bottom wall of the first surface-side recessed groove part in the first surface-side recessed groove part at a boundary position where an end portion of a member other than the membrane electrode assembly can be located and a bottom wall of the first surface-side recessed groove part in the first separator located other than the boundary position are in contact with the second separator of the other fuel-cell unit cell, the bottom wall of the first surface-side recessed groove part in the first surface-side recessed groove part at the boundary position has lower rising height from a recessed-groove opening end than the other bottom walls of the first surface-side recessed groove part, such that a surface pressure applied to the bottom wall of the first surface-side recessed groove part located at the boundary position is lower than a surface pressure applied to the other bottom wall of the first surface-side recessed groove part. a central region opposed to a power generation-enabled region of the membrane electrode assembly; a planar-shaped outer edge portion extending from the central region to outer edge of the central region; a first surface-side recessed groove part formed in the central region on the first surface; and a second surface-side recessed groove part formed in the central region on the second surface, wherein: grooves of the first surface-side recessed groove part and grooves of the second surface-side recessed groove part are located alternately on the first surface and the second surface in the central region by formation of a plurality of pit-and-bump stripes by press molding on the central region, the outer edge portion is joined to a site outside the power generation region of the membrane electrode assembly, and a bottom wall of the first surface-side recessed groove part in the first surface-side recessed groove part at a boundary position where an end portion of a member other than the membrane electrode assembly can be located and a bottom wall of the first surface-side recessed groove part in the first separator located other than the boundary position are in contact with the second separator of the other fuel-cell unit cell, the bottom wall of the first surface-side recessed groove part in the first surface-side recessed groove part at the boundary position has lower rising height from a recessed-groove opening end than the other bottom walls of the first surface-side recessed groove part, such that a surface pressure applied to the bottom wall of the first surface-side recessed groove part located at the boundary position is lower than a surface pressure applied to the other bottom wall of the first surface-side recessed groove part. grooves of the first surface-side recessed groove part and grooves of the second surface-side recessed groove part are located alternately on the first surface and the second surface in the central region by formation of a plurality of pit-and-bump stripes by press molding on the central region, the outer edge portion is joined to a site outside the power generation region of the membrane electrode assembly, and a bottom wall of the first surface-side recessed groove part in the first surface-side recessed groove part at a boundary position where an end portion of a member other than the membrane electrode assembly can be located and a bottom wall of the first surface-side recessed groove part in the first separator located other than the boundary position are in contact with the second separator of the other fuel-cell unit cell, the bottom wall of the first surface-side recessed groove part in the first surface-side recessed groove part at the boundary position has lower rising height from a recessed-groove opening end than the other bottom walls of the first surface-side recessed groove part, such that a surface pressure applied to the bottom wall of the first surface-side recessed groove part located at the boundary position is lower than a surface pressure applied to the other bottom wall of the first surface-side recessed groove part.