One of the renewable energy sources that can be used as a driving resource is the wind. Wind energy can be converted into energy in other forms, for example mechanical energy or electrical energy through wind turbines. One of the most developed wind turbines is the savonius type which includes the vertical shaft type. The investment cost for making a real wind turbine in the field is very expensive so it cannot use trial and error methods to get efficient turbines. Research to develop wind turbines is done by making a prototype of a laboratory scale wind turbine. The part of wind turbines are made in a small size so that the mini wind power plant can operate and on the other hand does not cost a lot. From the prototype parameters can be observed that affect the performance of the wind turbine. The windmill prototype was made 200 cm high and 50 cm in diameter and equipped with 4 blades. For testing in the laboratory using a wind source from the fan which is driven by an electric motor that can be adjusted by the rpm. The determination of power efficiency is applied by the turbine ability to absorb the energy of wind as represented by torque and rotational speed of turbine attacked air flow in testing. The result shows that efficiency of the savonius turbine were 5,02% - 9,12%.