To provide a wind power generating apparatus enabling effective use of slight wind for power generation.

The wind power generating apparatus 100 is provided with a rotatably arranged windmill 2, a power generator 3 generating electric power based on rotational energy of the windmill 2, and an anemometer 4 measuring speed of wind acting on the windmill 2. The wind power generating apparatus 100 is further provided with a drive unit 1 supplying drive force for starting rotation of the windmill 2 to the windmill 2 based on the wind speed measured by the anemometer 4.