The model test on the stability of sediments for the artificial beach constructed in the toribar district in the Hirara port is carried out in the three-dimensional hydraulic model basin.
　The purpose of the paper is as follows;i) The establishment of the new experimental technique in the movable-bed model for study the stability of artificial beaches surrounded by coral reefs, where its wave and current become complicated.ii) The investigation for the applicability of the island-type headland to the stability of the artificial beach.
　In the formation process of the artificial beach constituted by the headlands, it is necessary to use the undistorted model in order to reproduce deformation process of wave such as refraction, diffraction and wave breaking on the complicated reef topography. The distortion level of waves in the model test using sands, however, should be determined by the several trials in the movable-bed model experiment. The appropriate field observation data does not exist. So, the numerical analysis on original plan and 150m jetty plan, whose effects were expected for beach stabilization in the 1993 computation, have been set as a reproduction targets on flow field around the artificial beach, topographic evolution and shoreline change.
　The result of beach stability model test on the island-type headland with four detached breakwaters have shown the equivalent effect completed by 150m jetty plan, the island-type headland do not induce its large-scale erosion and shoreline regression observed in the original plan. From the experimental results, the optimum configuration of headland is proposed.