Based on the data obtained in the field, influeneces of the infragravity waves about one to three minutes in period on the littoral drift and the changes of nearshore topography have been studied. The main conclusions obtined are as follows;
(1)The exsistence of the standing edge waves is verified by analyzing the longshore variations of wave run-up fronts.
(2)The multiple longshorebars at Hakui Beach have been formed by the existence of infragravity waves perfectly reflected on the beach.
(3)The concentration of suspended sediment in the surf zone fluctuates with the period of one to two minutes. The net direction of the suspended sediment is offshoreward when the infragravity waves are predominant.
(4)The set of equations for the local sand transport rate in the surf zone is proposed.
(5)A tentative predictive model for the daily changes of shoreline is proposed.
(6)The actual condition of sea level rising on the shoreline in the storm is also shown.
(7)The critical level of berm erosion in the storm depends on the height of ingragravity waves and the mean sea level at the shoreline.