Identification of radon in soil provides information on the areas at risk for high radon exposure. In this study, we measured uranium-238 and radon-222 concentrations in soil to assess their approximate levels in Seoul. A total of 246 soil samples were taken to analyze uranium with ICP-MS, and 120 measurements of radon in soil were conducted with an in-situ radon detector, Rad7 at a depth of 1-1.5 m. The data were statistically analyzed and mapped, layered with geological classification. The range of uranium in soil was from 0.0 to 8.5 mg/kg with a mean value of 2.2 mg/kg, and the range of radon in soil was from 1,887 to 87,320 Bq/m 3 with a mean value of 18,271 Bq/m 3. The geology had a distinctive relationship to the uranium and radon levels in soil, with the uranium and radon concentrations in soils overlying granite more than double those of soils overlying metamorphic rocks.