Climate change due to global warming possibly effects the agricultural water use in terms of evapotranspiration. Thus, to estimate rice evapotranspiration under the climate change, future climate data including precipitation, minimum and maximum temperatures for 90 years ($2011{sim}2100$), were forecasted using LARS-WG. Observed 30 years ($1971{sim}2000$) climate data and climate change scenario based on SRES A2 were prepared to operate the LARS-WG model. Using these data and FAO Blaney-Criddle method, reference evapotranspiration and rice evapotranspiration were estimated for 9 different regions in South Korea and rice evapotranspiration of 10 year return period was estimated using frequency analysis. As the results of this study, rice evapotranspiration of 10 year return period increased 1.56%, 5.99% and 10.68% for each 30 years during $2011{sim}2100$ (2025s; $2011{sim}2040$, 2055s; $2041{sim}2070$, 2085s; $2071{sim}2100$) demonstrating that the increased temperature from the climate change increases the consumptive use of crops and agricultural water use.