Provided is a fuel cell system that can prevent oxidation degradation of a fuel electrode, even in the case where a control unit stops abnormally. A fuel cell system (1) comprises an SOFC (10) that generates electricity through an electrochemical reaction between a reduction gas and an oxidant gas, a control unit (40) that controls the supply of the reduction gas and the oxidant gas to the SOFC, a detection unit (45) that detects a stopping of a normal signal of the control unit or detects an abnormal signal of the control unit transmitted from the control unit, and a maintenance unit (50) that keeps a fuel electrode of the SOFC in a reduced state according to a detection result from the detection unit. The maintenance unit includes a hydrogen supply system (51) that supplies hydrogen to the fuel electrode as the reduction gas.