the present invention provides a method for controlling a process by calculating a manipulated variable from a deviation between setpoint and control output variables and then using the manipulated variable , wherein the time - series data of the control output variable is subjected to a frequency analysis , the rate of change in the frequency response amplitude of the control output variable in relation to a control gain ratio is determined , and a control gain is adjusted according to the rate of change and the results of the frequency analysis . with this adaptive control method and apparatus for the method , it is possible to automatically set a control gain according to the condition of disturbance . as a result , optimum control can always be achieved and follow - up capability can be improved for such events as a setpoint change .