In this study, we proposed a “wave power generating floating breakwater” as a floating breakwater equipped with oscillating water column type wave energy converters. We also carried out the simulation of oscillation for a floating body based on the three-dimensional potential connection method. By using the simulation results, we verified the wave reduction effects in the sea area behind the floating breakwater due to the wave energy absorption of wave energy converters.
The main conclusions of this study are as follows:
1) Considering from the average wave height within a certain range of the sea area behind the wave power generating floating breakwater, it has the large wave reduction effects when the incident wave period is short, when the mooring method is stiff and when the wave energy absorption rate of wave energy converters is high as an overall tendency.
2) The wave power generating floating breakwater cannot achieve the sufficient wave reduction in the sea area behind it unless the wave energy absorption rate is considerably higher than 75%.
3) The motion characteristics of the wave power generating floating breakwater vary and the diffraction waves around it also change depending on the shape of the floating breakwater and the configuration of the mooring method. However, within the range of the shape of the target floating breakwaters, the influence of the width, draft and length of them on the average wave height in the sea area is not so large.

Key Words: floating breakwater, wave power generation, wave energy, wave reduction, simulation of oscillation