Dynamical conditions for the fronts around the Yellow Sea Cold Water Mass, were investigated by means of the oceanographical data and simple numerical experiment. The coastal front developed along the coast inside the Yellow Sea and distinguished the Yellow Sea Cold Water Mass from the coastal water is attributed to the predominant tidal mixing near the coast. On the other hand the southern part of the front of the cold water mass would be explained a a part of the extention of a western boundary current which flows into the Cheju Channel.