Abstract: A floating body type offshore wind power generation is provided. An elongated floating body is provided with a sail and a rudder, and a wind-power generator and a battery are provided on the floating body. These are provided with a GPS and a communication facility, and are capable of determining and moving to places having good wind conditions. The floating body can travel in both directions in a longitudinal direction and can travel also to the windward, and is capable of staying at substantially the same position by repeating the movement in a switchback manner, so that the same function as a moored floating body type wind power generation is also achieved. Generated power is accumulated in the battery or the like and the power is extracted on a site of use such as the land for use.