An active dynamic absorber using piezoelectric actuator is proposed. The absorber is made up of a cantilever beam with a weight attached on the free end. The piezoelectric actuator is bonded near the fixed end and a strain gauge also attached near the fixed end is used for feed-back. It is found that the optimal feed-back can be done simply based on the theory of traditional dynamic vibration absorber. Experiments using a cantilever beam as the main system, under different excitation, are carried out, and the effect of vibration reduction has been obviously observed.