Disclosed herein is an aerogenerator having a rotation support unit for facilitating rotation of a rotational body. The aerogenerator includes a support pillar, a rotational body, vanes, a rotating force transmission unit, a generating unit and a rotation support unit. The support pillar has a hollow space therein and has a support extension on the upper end thereof. The rotational body is provided on the upper end of the support pillar so as to be rotatable using the rotation support unit. The vanes are provided on opposite ends of the rotational body. The rotating force transmission unit transmits rotating force of the vanes to the generating unit. In the present invention, the rotation support unit comprises a rotating plate which is provided between the rotational body and the support pillar, and first rollers which are provided in the rotating plate and are in contact with the rotational body and the support extension. The rotation support unit further comprises second rollers which are provided under the rotating plate and are in contact with the inner surface of the hollow space of the support pillar. Therefore, the rotational body can easily rotate on the upper end of the support pillar by the first rollers, and the rotational plate can be prevented from being separated from the upper end of the support pillar by the second rollers.