PURPOSE: To decrease the effect of the local vibration at a casing part and to improve the adjusting accuracy of balance by detecting the amount of vibration in the vicinity of the resonating number of vibration of a rigid stage, and adjusting the balance.

CONSTITUTION: The specifications of supporting springs 2 and a rigid stage 3 are set so that the rotary angular velocity in resonance becomes less than the rotary angular velocity at the time of rated number of rotation Ns. When a high-speed rotary device 4 is mounted on the rigid stage 3 at this time, the rigid stage 3 and the rotary device 4 are resonated at a number of rotation Ni less than the number of rotation Ns with the rotation of the rotary device 4. When the number of rotation of the rotary device 4 is set in the vicinity of the resonant number of rotation, a load sensor 5 detects the increase in vibrating amount of the rigid stage 3 in the vicinity of the number of rotation Ni. Here, the casing of the rotary device 4 is disassembled, and the balance of the rotating part is adjusted. After the assembling, the detection of the vibrating amount in the vicinity of the number of rotation Ni and the balance adjustment are repeated, and the unbalance component is corrected. Then, the replaced rotary device 4 is adjusted by the same way. Therefore, the vibration is detected under the maximum state of resonance sensitivity, and the local vibration of the casing part does not affect on the response of the rigid stage 3.