To form a uniform air stream efficiently over a wide range without generating noise.

Four vanes 14 made of cloth of synthetic fiber are arranged inside an annular frame member 18 in an angle of 90° in a radial state. Tension rods 14A, 14B are installed at both ends of each of the vanes 14 and then the tension rod 14B at a central part of each of the vanes 14 is connected by a rope 16. In turn, the tension rod 14A at an outer circumferential part is inclined by 45° against a vertical line and connected to the frame member 18. Four supporting columns 22 are arranged at four corner points of a square shape and then a holding means 20 is fixed to the upper end. Each of the holding means 20 is operated such that the frame member 18 is held in such a manner that it may be moved in a circumferential direction. Each of the holding means 20 has a motor, respectively, rotates a driving roller to cause the frame member 18 to be moved in a circumferential direction. As a result, the vanes 14 are rotated together with the frame member 18 so as to generate an air stream.