A freshwater supply system that stores fresh water transported by transport ships in storage devices and takes out the fresh water from the freshwater storage devices at need to use the same. The system comprises management device that puts management information together and sends and receives various information of countries for demand of the fresh water, analysis information of the fresh water, and various information of transportation device for transportation of the fresh water to the countries. Magnitudes of movements, prices, origins of movement, and destinations of movement of the fresh water are decided from the information from the management device.