A fuel cell system including a fuel cell that receives a supply of an anode gas and a cathode gas and generates power is provided. The fuel cell system includes a water content calculation unit configured to calculate a water content of the fuel cell, an internal impedance calculation unit configured to calculate an internal impedance of the fuel cell, and a starting temperature calculation unit configured to calculate a fuel cell temperature at a start of the system, based on the water content of the fuel cell as of a last time the system was stopped, and the internal impedance of the fuel cell at the start of the system.