For the vibration control of a main structure subjected to a random input with a dominant frequency, an active dynamic vibration absorber is manufactured, which is equipped with a linear motor as an actuator and is digitally controlled by means of optimal feedback and feedforward links. First, by performing impulse excitation, the usefulness of the optimal feedback control is verified. Second, in the frequency responses obtained from a stationary random excitation, the effectiveness of the optimal feedforward link is demonstrated in comparison with a feedback link only. Further, in a nonstationary random excitation in which the same nonstationary random wave can be realized every time, it is confirmed that the active dynamic vibration absorber is useful also for a nonstationary random input.