In adjustment of the control parameters of a magnetic suspension system, an object of the present invention is to provide a technique for adjusting the control parameters to optimum values automatically by employing the iterative feedback tuning method, without increasing the complexity of the program, the amount of calculation and the overall size of the system, and still reducing the amount of calculation required for calculation of the safety margin (gain margin and phase margin). In a method of automatic adjustment of control parameters according to the invention, when applying the iterative feedback tuning method to a feedback control system for a magnetic suspension system, only those control parameters that have a significant effect on the control performance of the system are selectively adopted/discarded from among control parameters so that the control parameters are guided to optimum values to obtain a response waveform desired by a designer directly from input/output data of a control subject.