Each vehicle includes a detection device configured to detect a situation outside the vehicle. When a server receives from a depleted EV a help signal requesting power supply from another vehicle to the depleted EV, the server selects, from among the other vehicles, a rescue EV to supply electric power to the depleted EV. The rescue EV moves to the depleted EV, stops behind the depleted EV detected by the detection device, and supplies power to the depleted EV while being stopped behind the depleted EV.