This study was carried out in order to estimate water losses in irrigation canals, which may be used to evaluate the water requirement for irrigation projects. The conveyance losses were measured by the inflow-outflow method, the seepage losses were measured by the ponding method, and the operation losses in the course of irrigation were calculated by comparing the two kinds of losses. The results obtained in this experiment were as follows; 1. Conveyance losses per unit area of wetted perimeter by the main irrigation canal, the secondary irrigation canal and the tributary irrigation canal, were 1.399${ imes}10^{-5}m^3/sec/m^2$, 5.154${ imes}10^{-5}m^3/sec/m^2$, and 2.67${ imes}10^{-5}m^3/sec/m^2$ respectively in the Goong-sa area. And they were 1.934${ imes}10^{-5}m^3/sec/m^2$, 2.149${ imes}10^{-5}m^3/sec/m^2$, and 4.558${ imes}10^{-5}m^3/sec/m^2$ respectively in the Seong-dug area. 2. Seepage losses per unit area of wetted perimeter by the secondary irrigation canal and the tributary irrigation canal, were 2.180${ imes}10^{-6}m^3/sec/m^2$ and 2.168${ imes}10^{-6}m^3/sec/m^2$ in the Goong-sa area, 1.150${ imes}10^{-6}m^3/sec/m^2$ and 1.084${ imes}10^{-6}m^3/sec/m^2$ in the Seong-dug area respectively. 3. Operation losses per unit area of wetted perimeter by the secondary irrigation canal and the tributary irrigation canal, were 4.936${ imes}10^{-5}m^3/sec/m^2$ and 2.453${ imes}10^{-5}m^3/sec/m^2$ in the Goong-sa area, 2.034${ imes}10^{-5}m^3/sec/m^2$ and 4.450${ imes}10^{-5}m^3/sec/m^2$ in the Seong-dug area respectively. 4. Conveyance, seepage and operation losses in the Goong-sa area were 6.7%, 94.6%, and 14.0% more than those in the Seong-dug area. Operation losses amount to about 17 times as much as seepage losses in the Goong-sa area and about 29 times in the Seong-dug area. 5. The seepage losses depend much on the soil texture, ranging from 7.437${ imes}10^{-7}m^3/sec/m^2$ to 2.430${ imes}10^{-6}m^3/sec/m^2$. 6. Water loss rates in the main irrigatin canal, the secondary irrigation canal and the tributary irrigation canal, were estimated as 8.49%, 37.27% and 9.81% respectively in the Goong-sa area. And they were estimated as 15.10%, 32.67% and 13.78% respectively in the Seong-dug area.