To provide a wind turbine device, further heightening the wind force with higher conversion efficiency to obtain large rotational output more than before in a structure including a Savonius vertical shaft type impeller.

The impeller 7 is fitted to a vertical rotating shaft 5, and a wind collecting plate 3 is spirally disposed and fixed along the circumferential direction outside the impeller 7. The impeller 7 includes two circular-arc main rotary blades 14, 15 and two circular-arc sab rotary blades 16, 17 smaller than the above, wherein the respective main rotary blades 14, 15 are disposed point-symmetrical about the vertical rotary shaft 5, the respective sab rotary blades 16, 17 are disposed individually adjacent to the respective main rotary blades 14, 15 with the recessed surface sides directed toward the projecting surface sides of the main rotary blades 14, 15, and ventilating spaces S21, S22 are secured between the main rotary blades 14, 15 and the sab rotary blades 16, 17 adjacent to each other.