PURPOSE: To obtain a large rotational energy with a small wind power prime mover, by arranging of a member of on one shaft water wheel type wind mill with its shft paralleled to its balde in such a configuration as receiving a concentrated wind blow only on its one side.

CONSTITUTION: A wind mill shaft 5 extending laterally or longitudinally, passing through a partition 2 or 3 at right angles to the direction of a wind inflow, is arranged parallel to each other in the middle portion of each wind tunnel 4. Next, a few blades 6 which fit the inner circumference of the wind tunnel 4 are arraged projectingly and radially on the circular surface of the shaft 5, and many wind mills 10 are arranged in parallel on one shaft, and connected and fixed as possible to move together. Moreover, an arcuate wind guide plate 7 which shields only the specified half of the wind mill 10, which centers the wind mill shaft 5, is arranged in the inlet 4a of each wind tunnel 4. Hereby, a generator 16 is able to be rotated, concentrating the rotational energy of each wind mill shaft 5 to one output shaft 12.