the rotor 1 is brought into a rotative condition then in accordance with the commands of the microprocessor 13 the a d conversions of the detected shift signal pz of the axial direction shift sensor 11 concerning the z axis direction of the rotor 1 and the detected shift signals px1 px2 py1 and py2 of the radial direction shift sensors 7 9 8 and 10 concerning the y axis and x axis of the rotor 1 are started simultaneously all in the five axes step 11 by the respective a d convertors 31 to 35 when this high speed a d conversion of the a d convertor 31 has been completed the converted signals digital values are entered into the microprocessor 13 step 12 the current command value iz of the electromagnet 6 concerning the z axis is calculated by a predetermined calculation process step 13 subsequently when the calculation process concerning the z axis direction has been completed the a d conversion is performed in parallel to the calculation process of the z axis at the same time the respective conversion signals from the a d convertors 32 33 34 and 35 which have already been subjected to the conversion are simultaneously inputted to the microprocessor 13 step 14 the microprocessor 13 calculates the respective current command values px1 px2 py1 and py2 of the electromagnets 2a 3a 2b and 3b concerning the control of the x axis and y axis in accordance with the inputted conversion signals step 15 when the calculation process has been completed in the microprocessor 13 the respective calculated current command values iz px1 px2 py1 and py2 are simultaneously fed to the associated d.