To provide a method in which to provide information or a warning about a disaster via turning on a light using a power source derived from natural energy without actually being at the site of the disaster when a disaster alarm (landslide), earthquake, tsunami or flash flood of a river occurs.

An electric power generation device 1 that generates electric power using natural energy, an electrical storage device 4 that stores electric power generated by the electric power generation device, and a light 6 that turns on with electric power supplied by the electrical storage device 4 are used to provide a warning about a tsunami and the like via turning on the lights 6 that are protected against earthquakes and the like and sounding warning signals, by use of a specific frequency and also displaying an arrow symbol indicating which direction to evacuate with the directions of North, South, East, and West shown, when an earthquake is detected.