Fuel cell system and activation method of fuel cell

A fuel cell system comprising:

• a fuel cell which generates electric power using reactive gases supplied thereto, the fuel cell including a solid polymer electrolyte membrane;
• a voltage measuring device for measuring a voltage generated by the fuel cell;
• and
• an electronic control unit that:
• controls a load applied to the fuel cell,
• controls at least a supply of the reactive gases to the fuel cell,
• obtains a rate of variation in the voltage generated by the fuel cell only when the load is varied by applying a load to the fuel cell in a pulse form immediately after the fuel cell is activated, wherein the rate of variation is a speed of increase in the generated voltage immediately after removing the load in the pulse form, and indicates a closed state in the fuel cell when the fuel cell is activated, and
• controls at least the supply of the reactive gases to the fuel cell based on the obtained rate of variation in the generated voltage.