The length of the runway of the Tokushima airpot is 1500m, so only small airplanes can use the airport. As the number of travelers has been increasing, the Tokushima airport is now filled to capacity. A plan to extend the runway 600 m into the sea has been proposed by Ministry of Transport. However, the Matsushige coast, where the airport is located, has been eroded due to the decrease of the sand supply from the Yoshino River and the construction of breakwaters at Imagiri and Awazu, and some offshore breakwaters have been constructed there to protect the shoreline. It is necessary to konw the effect of the extension of the runway reclamation on the shoreline.
　We constructed a movable-bed model in the Large Hydraulic Engineering Experiment Facility in the Port and Harbour Research Institute. We set a wave generator first in the main direction SE, and then in the two secondary directions SSE and ENE. The results of the experiment are as follows.
　1. The reclamation will reduce the coastal erosion between the airport and Imagiri Port.
　2. The Shoreline's configuration will become concave between the airport and Awazu Port.