The present invention is to provide a sealing member for a fuel cell which is able to keep surface pressure low, and to enhance sealing performance. The fuel cell includes an anode electrode and a cathode electrode which are sandwiched on both sides of a solid polymer electrolyte membrane, and an anode side separator and a cathode side separator which are then layered against both sides of this combination. Sealing members are installed into grooves on these separators. The cross section of each sealing member is formed with projecting portions extending in the widthwise direction of its groove on both sides of a semicircular shaped sealing member main body, and with a pair of cutaway portions in positions symmetrical about the center of a chord portion of the sealing member main body.