PURPOSE: To enable compacting of a nacelle part, by a method wherein a generator, driven by the rotary shaft of a rotor, is mounted to the strut side, and meanwhile, a nacelle, to which the rotor is attached, is formed in a division case, a yawing base part, secured to the lower part of the case, is supported to the upper end of a strut.

CONSTITUTION: A nacelle 3 is supported to the upper end of a strut 1, erected by means of plural tension wires 2, so that it can freely yaw, and a rotor 5 is attached to the end of a rotary shaft 4 pivotally supported to the nacelle 3. A generator 9 is driven by the rotating force of the rotary shaft 4 produced occasioned by rotation of the rotor 5. In which case, the generator 9 is mounted within a yoke case 8 secured to the upper end of the strut 1. The naccelle 3 is formed with a division case divided into 2 parts of an upper and a lower part, and a yawing base part 10 is integrally secured to a flange part located to the lower part of the front end of the lower split case. The yawing base part 10 is rotatably supported to a support part 11, secured to the uppermost end of the strut 1, through a bearing 12.