The equation to predict the soil temprature of Pusan and Chinju city as a function of time and soil depth for the geothermal energy utilization system and agriculture was devised. The equation was $T(x,t);=;Tm;-;To{cdot}ExP(-{xi}){cdot}cos{{omega}{cdot}[t-to-x/(2{cdot}{alpha}{cdot}{omega})^{0.5}]}$ with the soil thermal diffusivity, ${alpha},;of;0.4; extrm{m}^2/day,;0.0375; extrm{m}^2/day$ and phase zero point, to, of 24 days, 22.4 days in Pusan and Chinju city, respectively, during ten years from 1987 to 1996. The predicted and measured soil temperatures agreed well with the coefficient of determination of 0.95 at the soil depth of 0.0, 0.5, 1.0, 3.0, 5.0 m. The maximum and minimum temperature in Pusan 3.7, $30.1^{circ}C$ at soil surface and 14.3, $18.0^{circ}C$ at the depth of 5.0 m. The total mean temperature of soil in Pusan and Chinju city was about 16.3, $16.0^{circ}C$, respectively.