An anode (11a) and a cathode (11b) are provided on either side of an electrolyte membrane (11). A first separator (2) is disposed so as to face the anode (11a), and a second separator (3) is disposed so as to face the cathode (11b). A first sealing member (12) is disposed between the electrolyte membrane (11) and the first separator (2), and a second sealing member (13) is disposed between the electrolyte membrane (11) and the second separator (3). The cross-sectional shape or rubber hardness of the sealing members (12, 13) is varied according to a deformation amount generated in the electrolyte membrane (11) by a sealing reactive force. More specifically, in a site where the deformation amount of the electrolyte membrane (11) is large, either the contact area between the sealing member (12) and the electrolyte membrane (11) is increased, or the rubber hardness of the sealing member (12) is reduced. In so doing, deformation of the electrolyte membrane (11) caused by the sealing reactive force is suppressed, and the sealing performance of a fuel cell (10) is improved.