In order to study the seasonal variation of kinetic and potential energy of residual flow field in Suyoung Bay of Korea, we calculated its energy budget and compared it with the tidal energy there. The potential energy shows the large value in winter and spring and the small one in summer and early autumn when the density stratification is developed. The kinetic energy of residual flow varies seasonally and the seasonally averaged kinetic energy of residual flow per unit area is 6.4 × 10_-4 ergs s^-1cm^-2. It is mainly governed by the density-driven current with the exception of that in November when the kinetic energy of tide-induced residual current is larger than those of density-driven current and winddriven current. An averaged fraction of the kinetic energy of tide-induced residual current, wind-driven current and density-driven current, which are the major components of residual flow, is 29.1%, 3.4%, 67.5%, respectively, to the kinetic energy of residual flow. The fraction of kinetic energy of residual flow, potential energy and tidal energy per unit area is 1.0 : 6.7 × 10_3 : 8.2 × 10_4, respectively.