The soil which was confirmed by using auger with intervals of 200 m at a depth of 1 m in Agricultural tide land Section 5 had a somewhat poorly drainage and coarse loamy. The Gwangpo series has coarse loamy texture with a somewhat poorly drainage in Fluvio-marine plains, but confirmed soil had different characteristics with the Gwangpo series Our objective of in this study was to set a new soil series by comparing to the Gwangpo series. Both the Gwangpo and A-Gwangpo serieses showed the similar horizons (A, B and C horizons), texture (coarse loamy), and chemical properties. A somewhat poorly drainage in general Gwangpo series caused mainly grayish color and 2 -20% of the mottle's distribution (by oxidation) within 20 -50 cm depth. An our soils, the mottle's distribution was investigated by 2 -20% and 20 -49% in the Gwangpo and A-Gwangpo series, respectively. Gwangpo series is somewhat poorly drained and has a small amount of mottle (by oxidation) quantity, so it is used as a paddy field. But the A-Gwangpo series is estimated that it can be used as a field soil with an amount of 20 -49% of mottle (by oxidation) quantity.