This paper presents two new vibration suppression methods by perfectly inelastic collision and separation of masses : one is asymptotic suppression by iterative collision and the other is perfect suppression by 'one-shot' collision. In this paper, we also apply the proposed methods to the vibration reduction problem of so-called 'stacker cranes'. In order to suppress the residual vibration, we utilize the load and the platform as the impact damper. The effectiveness of the proposed methods is also confirmed through several experiments.