The Kuroshio Front to the east of Honshu, Japan, commonly has a double structure. The front consists of three main parts: the temperature front at its northern edge, the density front at its southern edge and the inside zone between them. In a previous paper suggested that the structures of the density front in November, 1984, of the inside zone in July, 1983, and of the inside zone in November,
... [Show full abstract] 1984, indicate the generation stage, the mature stage, and the decay stage of the double structure of the Kuroshio Front, respectively. Also, it was suggested that there is a mechanism which draws deeper thermocline water beneath the Kuroshio into the surface layer of the frontal zone. By using the same data taken in 1983 and 1984, we have conducted detailed water mass analysis with special reference to the double structure of the Kuroshio Front. The results, presented in this paper, support the arguments presented earlier.