In this paper, the pitch angle control design problem of wind turbine generator is considered. Dynamic characteristics of wind turbine system vary according to the wind speed and also the generator speed. But it is required to maintain the generator speed at the optimal one in spite of such variations. For this purpose, the pitch angle control of wind turbine which includes the robust stability performance is used. However, the conventional standard H_infin control provides conservative performance, so the control performance is inferior to conventional controllers such as gain scheduling PI controls. In this paper, we show a result of a pitch angle control of wind turbine generator by using the less conservative robust control. Obtained control performances are verified based on the dynamic simulator ldquoBladedrdquo and we confirmed that the obtained controller provides acceptable control performances by a fixed parameter controller. The performances are almost the same as the results by the gain scheduling PI control, and some performances of the H_infin controllers are superior to the PI control.