PURPOSE: An aerogenerator is provided to decrease an influence of a vortex generated in a rotation of a blade. CONSTITUTION: An aerogenerator comprises a hole (7) and an open and close device (10). The hole is formed in a rear side of a blade about a rotational direction. In the open and close device, one side is fixed in an inside of the blade. The open and close device comprises a body (20) in which the other side is twisted by a centrifugal force according to a rotation of the blade. The body is formed so that a part of the other side of the body closes the hole in case the blade is not rotated.
