In this paper the characteristics of a curtain-wall breakwater which have been studied experimentally are presented.
　A curtain-wall breakwater is composed of a thin vertical barrier extending from depth of -d to some height above the mean water level and of supporting piles. This type of breakwater is intended to reflect most of the wave energy which is concentrated near the surface with a partial barrier around the still wate level. The transmission and reflection coefficients of a model breakwater have been determined experimentally as well as the height of wave crests at the barrier. A modified solution of Ursell's theory and Wiegel's calcuation for the transmission coefficient are compared with experimental ones, but the agreement is not good for both theories.It has been concluded in the experiment that this type of breakwater is most effective and practical in deep water region; the relative depth h/L of 0.2 may be taken as alower limit for a curtain-wall breakwater to be practical.
　The wave forces acting on the barrier were also measured in the experiment. These forces were about 60 per cent of the theoretical ones computed with a modified Sainflou formula for the pressure of standing waves.
　In addition, an example of a curtain-wall breakwater design is discussed.