To smoothly carry out rotation even weak wind by supporting a plurality of circular cone shaped bending impellers having a large curvature radius in directions opposite to each other between arms which are rotatably supported at clearances vertically, and varying an angle of each bending impeller according to a wind direction.

For example, cross shaped arms 14, 14 are vertically attached at clearances on an output rotary shaft 11 connected to a power generator 18, and circular arc shaped bending impellers 21 having large curvature radius in directions opposite to each other, are rotatably attached between arms 14 and 141 line-symmetrically to a vertical center line. Each of bending impellers 21 are relatively linked through a crank mechanism 27, rotary torque generation execution angle control gear mechanisms 24, 25, and a lower flat gear 23 for regulating a wind direction so as to receive wind force maximum on a wind receiving side, and so as to prevent the wind force from receiving on a reverse rotating side. The bending impellers 21 are faced to a wind direction at all times, and an output rotary shaft 11 is rotated with the maximum rotating torque.