A fuel cell, comprising: an anode-side gas flow passage, which is in contact with an anode-side gas diffusion layer, for supplying fuel gas to the anode-side gas diffusion layer; and a cathode-side gas flow passage, which is in contact with a cathode-side gas diffusion layer, for supplying oxidant gas to the cathode-side gas diffusion layer, wherein the anode-side gas flow passage and the cathode-side gas flow passage are opposed flow passages in which a direction in which gas flows in one flow passage is opposite to a direction in which gas flows in the other flow passage, a contact area or a contact ratio of a metal member forming the anode-side gas flow passage is set to be smaller from upstream toward downstream of the anode-side gas flow passage, a contact area or a contact ratio of a metal member forming the cathode-side gas flow passage is set to be smaller from upstream toward downstream of the cathode-side gas flow passage, on the downstream of the cathode-side gas flow passage, the contact area or the contact ratio of the metal member forming the cathode-side gas flow passage is set to be relatively smaller than the contact area or the contact ratio of the metal member forming the anode-side gas flow passage, on the upstream of the cathode-side gas flow passage, the contact area or the contact ratio of the metal member forming the anode-side gas flow passage is set to be relatively smaller than the contact area or the contact ratio of the metal member forming the cathode-side gas flow passage, the metal member forming the cathode-side gas flow passage is a metal porous body, and the metal member forming the anode-side gas flow passage is a rib. an anode-side gas flow passage, which is in contact with an anode-side gas diffusion layer, for supplying fuel gas to the anode-side gas diffusion layer; and a cathode-side gas flow passage, which is in contact with a cathode-side gas diffusion layer, for supplying oxidant gas to the cathode-side gas diffusion layer, wherein the anode-side gas flow passage and the cathode-side gas flow passage are opposed flow passages in which a direction in which gas flows in one flow passage is opposite to a direction in which gas flows in the other flow passage, a contact area or a contact ratio of a metal member forming the anode-side gas flow passage is set to be smaller from upstream toward downstream of the anode-side gas flow passage, a contact area or a contact ratio of a metal member forming the cathode-side gas flow passage is set to be smaller from upstream toward downstream of the cathode-side gas flow passage, on the downstream of the cathode-side gas flow passage, the contact area or the contact ratio of the metal member forming the cathode-side gas flow passage is set to be relatively smaller than the contact area or the contact ratio of the metal member forming the anode-side gas flow passage, on the upstream of the cathode-side gas flow passage, the contact area or the contact ratio of the metal member forming the anode-side gas flow passage is set to be relatively smaller than the contact area or the contact ratio of the metal member forming the cathode-side gas flow passage, the metal member forming the cathode-side gas flow passage is a metal porous body, and the metal member forming the anode-side gas flow passage is a rib.