An electric vehicle with fuel cells mounted thereon has a fuel tank that stores a fuel therein, and a connector receptor that is connected to the fuel tank and is open to the surface of the vehicle body. A connector of a predetermined hydrogen supply device is fitted in and attached to the connector receptor, so that a supply of fuel is fed from the hydrogen supply device to the electric vehicle. The connector receptor is provided with a fuel lid for covering over the connector receptor. When it is determined that the fuel cells are in a working state, the fuel lid is not opened in response to input of an opening instruction of the fuel lid in the course of fuel supply. When it is determined that the fuel lid is open, on the other hand, operation of the fuel cells is not started in response to input of a starting instruction of the fuel cells in the electric vehicle. Such an arrangement enhances the safety of fuel supply to any system with fuel cells.