The seaward reverse wave, occurring on the submerged dual porous horizontal plate, can contribute to the reduction of the transmitted wave as it reflects the propagating wave. However, the collision between the propagating and seaward reverse waves increases the water level and acts as a weight on the horizontal plate. This study investigated the characteristics of the wave pressure created by the seaward reverse wave through the analysis of experimental data. The analysis confirmed the following results: 1) the time series of the wave pressure showed reverse phase phenomena due to the collision, and the wave pressures acted simultaneously on both upper and lower surfaces of the horizontal plate; 2) the horizontal plate became repeatedly compressed and tensile before and after the occurrence of the seaward reverse wave; and 3) the seaward reverse wave created the total wave pressure to the maximum towards the direction of gravity, primarily on the upper plate. It was also confirmed that the wave distributions showed a similar trend to the wave steepness. Such outcome of the analysis will provide basic information to the structural analysis of the horizontal plate as a wave dissipater of the steel-type breakwater (STB).