A method of mounting a vortex generator to a wind turbine blade includes: a step of specifying positions of at least two reference points at different coordinates in a blade spanwise direction of the wind turbine blade on the wind turbine blade; and a step of adjusting a mounting direction of the vortex generator and mounting the vortex generator to the wind turbine blade, with reference to a line connecting the reference points. The step of specifying the positions of the reference points comprises specifying the position of each of the reference points on the basis of: a length along a surface of the wind turbine blade in a chordwise direction from a trailing edge of the wind turbine blade or from a blade spanwise directional line extending along the blade spanwise direction on the surface of the wind turbine blade; and a distance in the blade spanwise direction from a blade root or from a blade tip of the wind turbine blade.