Surface sediment samples collected from the Okhotsk Sea to the South China Sea along the east Asiatic continent were submitted to clay mineral investigation. Results have shown the distinguishable distribution patterns of clay minerals in the seas and the ocean. The Okhotsk Sea is characterized by the most widespread distribution of smectite. Low concentration of kaolinite is also verified. In the Japan Sea, illite is the most widespread clay mineral, and smectite concentration widely varies from location to location. Kaolinite concentration tends to increase more than that of the Okhotsk Sea. The Pacific sediments along the Japanese Islands are characterized by the high concentration of smectite in the northern part, and of chlorite off the Ku Peninsula and Shikoku. The shallow water sediments from the East China Sea are characterized by the predominance of illite. In the Philippine Sea, the high concentration of smectite is recognized. In the area of the entrance of the Gulf of Thailand to the South China Sea, the high concentration of kaolinite is observed. The results revealed that the distribution of clay minerals in the seas and the ocean along the east Asiatic continent is closely related to the geological and pedological characteristics on the bordering land areas.