PURPOSE: To enable to take a dynamic balancing and to improve a manufacturing yield, by a method wherein, in case a rotary object exceeds a limit to which an unbalancing amount is cut off, a cutting-off is carried out in a manner to divide it into two parts by a vector division.

CONSTITUTION: Rotor 2 are aligned in order on a pitch conveyor 1 and at a B, a C, and a D point, and a dynamic balancing measuring device 8 detects an unbalancing position and an unbalancing amount to store them in a memory circuit 3a in a control circuit 3. The rotor 2a is then conveyed to the C point, and a cutter corrector 9 corrects the unbalancing amount, detected by the measuring device 8, exceeds a maximum cutting amount which is allowable to the rotor 2, a decision correction is carried out at the corrector 9 according to a command from a control circuit 3. In this case, positions b and c, displaced in position by θ1 and θ2, respectively, from an unbalancing position (a) are scraped off.