The purposes of this study were to determine an algorithm for estimating agricultural water demand of remote sites using remote sensing data and to apply it to Hwanghae South Province and estimate the present and potential water demand for agriculture use. 3 Landsat-5 TM images and DEM(100×100mm) were used for classification of the existing land cover and land suitability analysis for paddy fields. Also, 20 years meteorological data of North Korea were used for calculating the potential evapotranspiration by Blaney-Criddle eq. and net water demand. The results showed that the present and potential agricultural water demand and the developable area for paddy fields is about 89,300㏊.