The damage of the structures is classified into two types. The one is caused by the direct action of tsunami, and floating bodies such as destroyed facilities and drifting ships and cars cause the other one. The purpose of the present study is to investigate the damage on structures due to the drifting bodies with tsunami. In order to perform the investigation focused on a drifting body, experimental tests are carried out, and a combination method of non-linear long wave theory and DEM is suggested for drifting numerical models. The models are applied to reproduce the experimental tests. As a result, it is confirmed that suggesting method can predict the behavior of drifting bodies due to tsunami.