A series of model experiments have been carried out in order to investigate the characteristics of wave forces acting on perforated wall caissons. The character
istics of wave forces acting on the members and the stability of the caisson are discussed, and a calculation method of the wave forces is proposed in this report.
　The proposed method gives the wave pressure distributions base on Goda's pressure formula for ordinary vertical walls with some modification factors, which are defined respectively for the following three phases:
　Phase I ;wave pressure at the perforated wall is maximum,
　Phase IIa;impulsive wave pressure at the impermiable rear wall of wave chamber is predominant, Phase IIb;slowly verying wave pressure at the rear wal is predominant.
　The wave pressure distribution can be used for the design of the caisson membersand also of the whole caisson.
　In this report, impact wave pressure on the perforated wall caisson is also discribed. The wave force becomes very impulsive when the rubble mound foundation of the caisson is high. Such impulsive pressures can be greatly reduced by the perforated wall. The pressure formula presented here can evaluated the impulsive pressures.