Estimations of paddy field area are important for agricultural water supply planning. Especially these estimations have to be excused by drainage basin. In this research, we developed a paddy field estimation model considering shift-share effects such as national growing, structural, local effects. National growing effects are estimated by adopting the result of KREI-ASMO model which predict farm land area in national level. Paddy field structural effects are estimated using statistical data about farmhouse numbers and cultivation areas. Local allocation effects are calculated by differences of estimations and real data. The results using data from 1998 to 2003 show that developed model estimates 2006 paddy field areas in each province in 5% error and is applicable to predict future change of paddy field.