To provide fresh water by utilizing natural energy without using a specific energy.

The fresh water is provide by collecting, at one end of a duct 2, a vapor 4 evaporated by heating with solar energy and hot air, leading the vapor 4 through the duct 2 to the top of a mountainous region 3 having a high altitude, liquefying the supersaturated vapor 4 to collect a water 11 into basins 6, leading the water to a feed pipe 7 and transporting the water to a utilization area, wherein the supersaturated vapor 4 led to the top of the mountainous region 3 through the duct 2 is naturally cooled bellow the dew point to liquefy in a heat exchanger 5 and the obtained water is discharged and transported to the utilization area through a transporting pipe 12. Thereby, the fresh water is provided by utilizing natural energy without using a specific energy.