To increase the precision of the tuning of centrifugal balance and to improve a speed without generating chips.

The balance structure of a rotor includes a turbine spindle body (1), a plurality of magnets (12) arranged in a circumference direction in the periphery zone of the turbine spindle body (1), an end plate (2) which adheres to the side which intersects perpendicularly with the axial direction of the turbine spindle body (1), and a balance weight (5). The end plate (2) has a plurality of holes (4) formed in the circumference direction to the periphery region of the end plate (2), and the balance weight (5) is axially installed in one or the plurality of holes (4) which are selected from the plurality of the holes (4). Centrifugal balancing adjustment is performed by wearing the weight, chips are not generated, and the impairment of motor performance is avoided. The wearing of the weight is a simple process, and performed at a high speed with high precision. The end plate (2) is formed thinly. The thin end plate (2) reduces an eddy current loss.