PURPOSE: To utilize wind forces and solar energy simultaneously so as to increase economic effects by providing a sail main body in the form of a wing whose cross section has a symmetrical streamline shape, and covering the sail main body with filmlike solar cells.

CONSTITUTION: A sail main body 1 is in the form of a wing whose cross section shows a symmetrical streamline shape, and is covered with filmlike solar cells 3. Therefore, the whole of both of the right and left sides of the sail main body 1 is utilized as the effective area for solar power generation. A storage battery is also used in the event that power generation is disabled by the influence of the weather, etc. Use of the wing-shaped sail enables excellent use of wind forces and the performance of the sail is improved as compared with normal sails, and simultaneous use of the wind forces and solar energy provides large economic effects while helping to prevent degrading of the environment.