The reflection coefficient of curved slit caisson breakwaters for oblique incident waves mostly depends on teh apparent width of the wave dissipating parts of caissons which is measured along the incident wave direction. It becomes minimum when the ratio of this width to the wave length corresponding to the significant wave period is 0.10～0.25.
　The impulsive wave pressure occurs in the wave chamber of this caisson, when the angle of wave incidence is equal to 0. But for oblique incident waves, the impulsive wave pressure becomes remarkably small and only the ordinary pressure acts on the members. After diminution of the impulsive wave pressure, the wave pressure at the upper part of the wave chamber without partition walls decreases gradually as incident waves become oblique. However, the wave pressure at the lower part of the wave chamber with partition walls does not decrease so much as that of the upper part of the wave chamber, owing to the influence of the partition walls.
　In this study based on the experimental resutls, the reduction coefficient of the design wave forces according to the incident wave angle are suggested. Examiniation is also made for the wave pressure acting on a curved slit caisson which is located adjacently to the ordinary caisson by means of the model experiments.