It is said that Jomon Age began about 12, 000 years ago and continued till about 2, 500 years ago. The potteries of that age are known as Jomon pottery. Among them, a pottery discovered from the Umataka ruin in Niigata Prefecture in 1931 has an excellent shape. It is said that this pottery was made about 4, 500 years ago. Jomon potteries of similar artistic styles have been discovered in various parts of Japan. These potteries have very nice shapes, but the pottery discovered from the Umataka ruin excels other potteries by its excellent proportion. From the shape of lip, it was named "Kaen pottery". However, from the patterns of its lip and side wall, it is more appropriate to consider that they are related to water flow. In this report this hypothesis is examined by a visualization method using the pollen of cedar and pine trees, and computer simulation.