To provide a fuel cell capable of recovering catalyst performance on a timely basis; and to provide a fuel cell system.

This fuel cell 10 is provided, as main parts, with an anode electrode part 12, a cathode electrode part 14, an anode electrode part 12 and a proton conducting part 16. An electrode 18 of the anode electrode part is formed with a material having optical transparency and photocatalyst action. A light emitting element 20 for introducing light into the anode electrode part 12 is arranged on the anode electrode part 12. When a catalyst 22 of the anode electrode part 12 is poisoned and catalyst performance is deteriorated, light generated by the light emitting element 20 is introduced into the anode electrode part 12, whereby the electrode 18 is activated by a photocatalyst action to decompose and eliminate the poisoned constituent of the catalyst 22.