In a method for operating a fuel cell including an electrolyte membrane sandwiched by a fuel electrode and an oxidizing agent electrode, the method includes a hydrogen feedback process either before starting operation of the fuel cell or after stopping operation of the fuel cell. The hydrogen feedback process includes the processes of a process for electrically connecting a positive electrode of an external electric power source to the oxidizing agent electrode of the fuel cell, a process for electrically connecting a negative electrode of the external electric power source to the fuel electrode of the fuel cell, a process for oxidizing hydrogen remaining in the oxidizing agent electrode to generate protons, the hydrogen contained in the fuel, and a process for reducing the protons, transferred to the fuel electrode from the oxidizing agent electrode through the electrolyte membrane, into hydrogen.