BALANCER

PROBLEM TO BE SOLVED: To maintain a compressor housing in position to obtain a correct measurement result at the time of imbalance measurement.SOLUTION: A balancer for measuring a direction and amount of imbalance on a supercharger 1 having a rotor 2 and a compressor housing 5 comprises: a rotation detecting sensor 34 for measuring the number of revolutions or a rotation angle of the rotor 2; an acceleration pickup 16 for measuring a vibration characteristic of the rotor 2; a servo motor 31 for connecting the compressor housing 5 to or disconnecting the compressor housing 5 from the supercharger 1; and a position control device 36 for giving instructions to the servo motor 31 about an installation position of the compressor housing 5 in accordance with a measurement result of the rotation detecting sensor 34 and a measurement result of the acceleration pickup 16. In the balancer, the servo motor 31 maintains the compressor housing 5 at the installation position in the rotation of the rotor 2.