Recently huge typhoons had attacked to the coastal waters in Korea and caused disastrous casualties in those area. There are some discussions on correction to the design parameters for the coastal structures. Wave transformation computations with the extreme waves are of value in planning and constructing engineering works, especially in coastal regions. Prediction of typhoon surge elevations in this study was based primarily on the numerical model, since it is difficult to study these events in real time or with on the physical model basic. Wave prediction with a two dimensional numerical model for a site with complicated coastal lines and structures at the period of typhoon Maemi was discussed. In order to input parameters for the extreme wave conditions, we analyzed the observed and predicted typhoon data. Finally we applied the model discussed above to the storm surge and extreme wave problem at Busan Harbor, the southeast coast of Korea. Effects of water level variation and transformation of the extreme waves in relation with the flooding in coastal waters interested were analyzed. We then made an attempt to present a basic hazard map for the corresponding site.