The triangular sand bar which often exists around the river mouth has the suitable topography for surf-riding. The delta type artificial reef which imitated this triangular sand bar was newly designed for the shore protection structure. In an experimental wave basin, the characteristics of the wave breaking, the wave runup, the littoral current and the sand drift were studied. As compared with thegroins, the delta type reef has the superior property in the sand drift control and the waverun-up height decrease.