The effects of the shape of rotor end plates on rotor performances have been investigated empirically by using five kinds of the Savonius rotors. The optimum shape of the end plate has been found from experimental results, and it has been revealed that the contribution of the lift force to the rotor power is considerably large. Then, by using a deflecting plate placed in front of the rotor, it has been attempted to improve the performances of the Savonius-type wind turbine. By the use of the deflecting plate, the power has been increased about 24 %. It has been also proved that the deflecting plate can be used as a speed control device or a protection device of the Savonius-type wind turbine.