The effect of potential future climate change on the storage rate of paddy field during storm periods (June - September) was assessed using the daily paddy water balance model. The CCCma CGCM2 data by SRES (special report on emissions scenarios) A2 and B2 scenarios of the IPCC (intergovernmental panel on climate change) was used to assess the future potential climate change. The future weather data for the year 2020s, 2050s and 2080s was downscaled by Change Factor method through bias-correction using 30 years weather data. The future (2020s, 2050s and 2080s) rainfall, storage and irrigation of paddy field, runoff in paddy levee and ponding depth were analyzed for the A2 and B2 climate change scenarios based on a base year (2005). The future irrigation change of paddy field was projected to increase by decrease in rainfall. So, runoff change in paddy levee was decrease slightly, future storage change of paddy was projected to increase.