Fuel cell system

A fuel cell system that includes a load, a fuel cell stack connected to the load and a buffer tank storing an anode gas discharged from the fuel cell stack and that is configured to supply an anode gas and a cathode gas to the fuel cell stack to generate power according to the load, the fuel cell system comprising:

• a pressure setting unit configured to set a pressure of the anode gas higher when the load is high as compared with when the load is low;
• a stagnation point determination unit configured to determine, at a time of a lowering transient operation where the pressure of the anode gas in a reaction flow path within the fuel cell stack is lowered by a power generation reaction of the fuel cell stack, whether or not a nitrogen stagnation point is left in a reaction flow path within the fuel cell stack;
• and
• an operation control unit configured to perform an operation while preventing the pressure of the anode gas from being lowered when a required load is lowered in a state where the nitrogen stagnation point is left.