Biasing unit, a spindle member, and a link mechanism of a windmill for a wind power generator vary an angle of a blade in a first stage where the angle is made nearly parallel to the wind so that the blade easily rotates in light winds, a second stage where the angle is made nearly perpendicular to the wind so that the blade easily rotates at high speed when the wind speed increases, and a third stage where the blade is pushed back from the state of being nearly perpendicular to the wind to the state of being nearly parallel to the wind so as to prevent the excessive rotation in strong winds, without electrical control being not required. Accordingly this wind power generator has an excellent starting performance and can control the excessive rotation at low cost.