In a centrifugal chamber 9, an elastic rotation shaft 30 and a high-rigidity rotation shaft 34 extend coaxially. When a rotor selected from an angle rotor 17 and a swing rotor 36 which have different sizes and shapes is set in the centrifugal chamber 9, an optimal shaft is connected automatically to the selected rotor. The angle rotor 17 having a low tendency toward mass eccentricity is supported and rotated by the elastic rotation shaft 30 for high-speed rotation. The swing rotor 34 having a high tendency toward mass eccentricity is supported by the high-rigidity shaft 34 for low-speed rotation. Rotation torque is transmitted to the swing rotor 34 from the elastic rotation shaft.