A fuel cell is provided where assembly of the seals is facilitated and excellent sealability and miniaturization becomes possible. This is achieved by a fuel cell (N) where an electrode film structure (12) having an anode electrode (A) provided on one side of a solid polymer electrolyte film (15), and a cathode electrode (C) provided on the other side thereof is clamped with an anode-side separator (13) and a cathode-side separator (14), wherein a groove (38) is provided in a surface (13a, 14a) of each separator (13) and (14) corresponding to the outer peripheral portion of the anode electrode (A) or the cathode electrode (C), and a seal (S1) having a circular shape in cross-section and with a fin (F) is provided in this groove (38).