An automatic adjustment method for a feedback control system including an automatic adjustment device that automatically adjusts filter parameters of a first actual notch filter and a second actual notch filter which are provided in series in two stages on a subsequent stage of a feedback controller, the method comprising: extracting a vibration component caused by a resonance characteristic of a control target, from a response of the feedback control system by using a highpass filter, by the automatic adjustment device including the highpass filter, the first adaptive notch filter and the second adaptive notch filter in series in the two stages, and an adjuster; using the extracted vibration component as an input of the first adaptive notch filter, by the automatic adjustment device; specifying a frequency of a main vibration component of an input signal and performing adaptive convergence to eliminate only the main vibration component from the input signal and then output a resultant, by the first adaptive notch filter and the second adaptive notch filter; determining whether or not elimination of the vibration component is possible, based on input and output signals of the first adaptive notch filter and input and output signals of the second adaptive notch filter, by the adjuster; determining whether parameters of the first adaptive notch filter and the second adaptive notch filter are converged and obtaining a difference between the parameters of the first adaptive notch filter and the second adaptive notch filter, based on a parameter value of the first adaptive notch filter and a parameter value of the second adaptive notch filter, by the adjuster; and setting the filter parameters of the first actual notch filter and the second actual notch filter based on a result obtained by determining whether or not the elimination of the vibration component is possible, a result obtained by determining whether the parameters of the first adaptive notch filter and the second adaptive notch filter are converged, and the difference between the parameters, by the adjuster. extracting a vibration component caused by a resonance characteristic of a control target, from a response of the feedback control system by using a highpass filter, by the automatic adjustment device including the highpass filter, the first adaptive notch filter and the second adaptive notch filter in series in the two stages, and an adjuster; using the extracted vibration component as an input of the first adaptive notch filter, by the automatic adjustment device; specifying a frequency of a main vibration component of an input signal and performing adaptive convergence to eliminate only the main vibration component from the input signal and then output a resultant, by the first adaptive notch filter and the second adaptive notch filter; determining whether or not elimination of the vibration component is possible, based on input and output signals of the first adaptive notch filter and input and output signals of the second adaptive notch filter, by the adjuster; determining whether parameters of the first adaptive notch filter and the second adaptive notch filter are converged and obtaining a difference between the parameters of the first adaptive notch filter and the second adaptive notch filter, based on a parameter value of the first adaptive notch filter and a parameter value of the second adaptive notch filter, by the adjuster; and setting the filter parameters of the first actual notch filter and the second actual notch filter based on a result obtained by determining whether or not the elimination of the vibration component is possible, a result obtained by determining whether the parameters of the first adaptive notch filter and the second adaptive notch filter are converged, and the difference between the parameters, by the adjuster.