To provide a low-cost wind turbine generator system capable of generating electric power even with slight wind and besides enduring high wind without requiring expensive materials and complicated parts.

The wind turbine generator system 1 includes a rotating shaft 40 horizontally extending, a wind receiving section 50 fixed to the rotating shaft 40, a support block 30 for supporting the rotating shaft 40 so that the rotating shaft 40 can rotate by wind force hitting against the wind receiving section 50, a support shaft 20 for supporting the support block 30 so that the support block 30 is capable of turning within a horizontal plane together with the rotating shaft 40 by the wind force hitting against the wind receiving section 50, a wind-pressure variation accepting generator 60 with a driving shaft 62, a ratchet wheel mechanism 80 for transmitting the counterclockwise rotating motion of the rotating shaft 40 to the driving shaft 62 of the wind-pressure variation accepting generator 60, a wind-direction variation accepting generator 70 with a driving shaft 72, and a ratchet wheel mechanism 90 for transmitting the clockwise rotating motion of the support block 30 to the driving shaft 72 of the wind-direction variation accepting generator 70.