Deformation absorption member and fuel cell

A fuel-cell-stack, comprising:

• a separator unit comprising an anode side separator and a cathode side separator;
• and
• a deformation absorption member disposed between the anode side separator and the cathode side separator, the deformation absorption member being formed from a substantially planar base material, and including a plurality of first and second raised pieces in which extension portions extended from proximal ends thereof are arranged in a grid pattern in which two adjacent first raised pieces and a second raised piece are alternatingly arranged in a direction perpendicular to a direction in which the extension pieces extend, the proximal end of the second raised piece being substantially as wide as a total width of the proximal ends of two adjacent first raised pieces,
• each raised piece of the plurality of first and second raised pieces being formed in a non-rectangular shape in which the width of the extension portion is shorter than the width of the proximal end, and the plurality of first and second raised pieces being configured so that the directions of the extension portions of each of the first raised pieces are alternately arranged to the directions of each of the extension portions of the second raised pieces in a direction perpendicular to the direction in which the extension portions extend along the base material, positions of the proximal ends of each of the first raised pieces adjacent a second raised piece in the direction perpendicular to the direction in which the extension pieces extend are arranged in at least overlapping positions in the direction in which the extension portions extend.