To increase durability and reliability and miniaturize, lighten and reduce a cost.

A center shaft 4 is fixed unrotatably by a fixed member 12 and a ring body 3 is supported rotatably to the center shaft 4 and a blade body 6 is arranged radially around this ring body 3 and an inner end is fixed to the ring body 3. While, the respective outer ends of the blade body 6 are connected by a ring shape frame body 8 and the frame body 8 is supported movably in the periphery direction of the frame body 8 by an outside support means 10 through rollers 26, 28 and rotated and driven by a motor 36 through a gear 34. As in this rotary blade 2, the blade body 6 is supported by both central ring body 3 and a center shaft 4 and the outside frame body 8 and support member 22, the burden applied to the ring body 3 of the center part and the center shaft 4 is reduced extremely and the deformation and damage of the blade body 6 hardly occur.