Fuel cell system and fuel cell control method

A fuel cell system, comprising:

• a fuel cell, which includes a membrane, and an anode and a cathode which sandwich the membrane therebetween, wherein the fuel cell produces electric power from a reaction of reactive gases via the membrane when the reactive gases are supplied to the anode and the cathode;
• a supplying means for supplying the reactive gases to the fuel cell;
• and
• a controlling means for controlling the supplying means, wherein the controlling means comprises:
• a power production effective area estimating means for estimating areas of the electrodes available for producing power as a power production effective area;
• a current density calculating means for calculating a current density of the power production effective area calculated by the power production effective area estimating means based on a total power required by the fuel cell;
• a gas supply amount determining means for determining an amount of reactive gas to be supplied to the fuel cell based on the calculated current density;
• and
• a gas supply controlling means for controlling the supplying means to supply the amount of reactive gas determined by the gas supply amount determining means to the fuel cell.