A negative feedback control system includes a step of amplifying digital information by an amplifying operation at a high response speed and not including an integration. The negative feedback control system detects a predetermined amount of increase and decrease in the controlled variable, and outputs an increment signal or a decrement signal according to the predetermined amount of increase and decrease in the controlled variable, respectively, receives increment signals and the decrement signals from a controlled variable detecting unit 4, ignores the first successive n increment signals immediately after an arbitrary decrement signal, then begins to count each increment signal as a +1 unit from the n+1-th increment signal after the arbitrary decrement signal, and ignores the first successive n decrement signals immediately after an arbitrary increment signal, then begins to count each decrement signal as a -1 unit from the n+l-th decrement signal after the arbitrary increment signal (FIG. 2); whereby the vibration of the controlled variable is suppressed.