Hydraulic characters of a non-wave overtopping type seawall installed on a moundare investigated through experiments with a two-dimensional wave tank. A critical wave height, which is defined as a maximum wave height on which no wave overtopping occurs at all, was measured on different incident wave conditions as well as mound configurations. The wave reflection coefficient and wave pressure distributions on the seawall were also measured when the waves with the critical waveheight act on the seawall. In this study, the characteristics of the critical wave height and wave reflection coefficient are discussed under various incident wave conditions as well as mound configurations. And then, characteristics of wave pressure distributions are also discussed with comparing the design wave pressure act on the vertical seawall.