A start-up method of a wind turbine generator includes a step of increasing a pitch angle of a wind turbine blade from a feather pitch angle to a fine pitch angle. The step of increasing the pitch angle of the wind turbine blade includes steps of: determining based on first to n-th pitch angles (n≧2) greater than the feather pitch angle and smaller than the fine pitch angle and first to n-th rotational speed conditions associated with the first to n-th pitch angles, respectively, whether a control target rotational speed, which is a wind turbine speed or generator speed, satisfies the i-th rotational speed condition when the pitch angle reaches the i-th rotational speed out of the first to n-th pitch angles, the first to n-th pitch angles and the first to n-th rotational speed conditions being stored in a storage unit; decreasing the pitch angle to the (i−1)-th pitch angle or the feather pitch angle in a case that the control target rotational speed does not satisfy the i-th rotational speed condition when the pitch angle reaches the i-th pitch angle; and increasing the pitch angle to the (i+1)-th pitch angle or the fine pitch angle in a case that the control target rotational speed satisfies the i-th rotational speed condition when the pitch angle reaches the i-th pitch angle.