Changes of sea-bed topography at the coast around the mouth of Agano River are discussed on the basis of results of statistical analysis on the data of sounding surveys performed during from 1962 to 1973. Agano River is one of the biggest rivers of Japan and flows into Japan Sea at five killometers west of the East Port of Niigata which is under construction.
　Following three subjects are mainly discussed:
　1) Change of sea-bed topography from the view point of the long time scale and wide area.
　2) Reduction of the scale and change of the configuration of the submarine sand bank at the front of Agano River.
　3) Characteristics of longshore bars near the river mouth.