In order to decay the transient vibration of a system subject to an impulsive force, the use of a dynamic absorber is studied in this paper. The damping effects of the dynamic absorber when attached to the one degree of mass-spring system and the cantilever beam with tip mass, are investigated numerically and experimentally. The logarithmic decrement is introduced to describe the decay rate of the residual vibration. Optimum tuning design parameters of the absorber are obtained from the condition that the logarithmic decrements take maximum values. These optimum tuning parameters are also compared with those parameters which are tuned to minimize the resonant response of the system subject to harmonic force. It is noted that the measurement of logarithmic decrement is less comlicated than the measurement of the response curve. As a result, the characteristics of the logarithmic decrement shown by the present work are useful in tuning the dynamic absorber in practice.