Tsunami can yield extensive topographic change, which causes secondary damages such as collapse of coastal structures.Therefore, it is important to analyze the topographic change due to the tsunami. In this study, we investigated spatialvariation of sedimentation and erosion due to the 2004 Indian Ocean tsunami at the Kirinda port, Sri Lanka by using thebathymetric data before (Nov, 2004) and after (Feb, 2005) the tsunami. We also conducted numerical analysis of tsunamipropagation and sediment transport. The results show that the tsunami caused approximately 5m erosion or deposition, and the shoreline was moved approx. 100m toward the offshore. Morever, backwash that was redirected by coastal structuresplayed a main role of significant erosion around the wave breaker.