A series of model experiments on wave reflection, overtopping and wave forces have been conducted for the following types of breakwater :
　(1) Conventional caisson type breakwater
　(2) Caisson type breakwater armoured with wave dissipating blocks
　(3) Caisson type breakwater with a wave chamber
　(4) Caisson type breakwater with a sloped face.
　All of these caisson were set on a rubble mound founda was 1/50. Experiments for the wave reflection and overtopping were carried out by using of irregular waves and the experiments for wave forces were carried out by regular waves.
　As for a sea wall in the depth of 21 meters exposed to severe action of waves, the following two types were investigated for wave overtoping :
　(1) Perforated caisson type sea wall at the head of reclaimed land
　(2) Double type structure composed of an offshore breakwater of conventional caisson type, and a bulkhead for reclaimed land.