To significantly enhance the utility value of windmills and to diversify the content of a game by constructing a windmill generator with a plurality of windmills closely disposed and combined as units and making the positions, moving courses and discharge positions of game balls, seen or concealed among the windmills, predictable based on the rotating state of the windmills.

The windmill generator 20 includes a substantially vertically disposed base member 21 and the plurality of windmills 30 having vanes rotatably supported by the base member to rotate in contact with game balls flowing down on the surface of the base member. A plurality of rows of windmills consisting of a plurality of closely disposed windmills, and impellers constituting the windmills are rotated when one game ball passes between at least two adjacent windmills.