Reliability design of maritime structures based on the deformation level will be one of the most important future design tools. However, it has not been fully applied to actual design since it is very difficult to take the various design condition into account. The present paper points out on the basis of the experimental results, the influences of the state of wave-dissipating blocks on the wave pressures at several cross sections of a breakwater, and the stochastic characteristics of obtained data was examined. 1) The covering condition of wave-dissipating blocks makes a significant influence of the wave pressure acting on the block layer. 2) When the impulsive wave breaking is generated, wave pressure p1 on the still water level becomes proportional to the square of the wave height. Then the numerical wave flume (CADMAS-SURF/2D) was applied for the covering state of wave-dissipating blocks.