A method protects a battery in a fuel cell vehicle, in which an inverter-driven motor is supplied with electric power from the battery and a fuel cell. If a battery voltage of the battery falls outside of a prescribed range, a primary current and a secondary current that flow through the DC/DC converter, or currents in branch paths that correspond to the primary current and the secondary current, are reduced in order to limit a charging current flowing into the battery or a discharging current flowing from the battery.