Jeju Island is volanic island, and is located about 96km south of Korean Peninsula. Volcanic ash is widespread as a soil parent material throughout island. Soils on the island have the characteristics typical volcanic ash soils. This study was conducted to classify Wuimi soils, black volcanic ashy soils, in Jeju Island according to Soil Taxonomy. Wuimi soils have black or very dark brown(10YR 2/2) gravelly silt loam A horizons(0-20cm) and black(10YR 2/1) cobbly silt loam BA horizons(20-45cm). Bw horizons(45-100cm) are yellowish brown(10YR 5/4) silt. They occur lava plain derived from volcanic ash materials. Wuimi soils contain 6.1-7.2% oxalate extractable (Al+1/2Fe), over 85% phosphate retention, and lower bulk density than 0.90Mg/m3. All horizons have andic soil properties. They can be classified as Andisols. Wuimi soils have an udic soil moisture regime and have a 1,500kPa water retention of 15% or more on air-dried samples throughout all horizons, and can be classified as Udands. A and BA horizons have a color value, moist, and chroma of 2 or less, melanic index of 1.70 or less, and 6% or more organic carbon. They meet the requirements of melanic epipedon. Wuimi soils key out as Melanudands. Also they meet the requirements of Thaptic Melanudands. Wuimi soils have a fine-earth fraction that has a water content at 1,500kPa tension of 12% or more on air-dried samplesor of 30 to 100% on undried samples; and have less than 35% rock fragments. Thus, their substitute for particle-size class are medial. Wuimi soils can be classified as medial, thermic famly of Thaptic Melanudands..