To provide a small-sized impeller wind power generation device capable of realizing highly efficient rotation of an impeller wind mill by collecting wind volume in a wide range.

A fixed wind collecting surface 2 and a multi-function movable wind collecting board 4 collect wind volume in the wide range to the impeller 5 built in a frame for high rotational efficiency. The fixed wind collecting surface 2 covers the half portion of the impeller 5 to concentrate the wind power in a working portion. The multi-function movable wind collecting board 4 in which a top end gap 4-c is located is retained by an opening/closing link 7 connected with both side surface plates 1 of the frame, a link mechanism with an opening/closing control spring 7-c, and a retainer 8 to enlarge a wind port. The area of the wind port is automatically controlled corresponding to changes in the wind power, and the rotation of the impeller 5 is stabilized by an automatic wind volume adjustment to prevent chaotic generation. If the wind power exceeds its limit, a strong wind defense function, such as closing to the fixed wind collecting surface 2 is also carried out, and the impeller 5 is continuously rotated by the wind power entering from the top end gap 4-c.