A method for operating a fuel cell vehicle includes supplying electric power to a vehicle drive motor from at least one of a fuel cell and a battery. It is determined whether an electric potential of electric power output from the fuel cell is within a deterioration acceleration region in which the fuel cell is deteriorated due to a platinum oxidation-reduction reaction. The fuel cell is controlled in a deterioration suppressing mode when the electric potential is within the deterioration acceleration region in a state where the fuel cell and the battery supply electric power to the vehicle drive motor.