To examine the effect of climate change on fluctuations of soil water, we estimated the future soil water
conditions of two fields in Yamaguchi, Japan. Firstly, we observed the suction of soil water at the fields in Yamaguchi for two years and modeled the soil water flux by using the observed data and HYDRUS-1D. Next, we applied future weather data of ELPIS-JP to the atmospheric boundary conditions of the field models and estimated the soil water conditions of those fields under climate change. As a result of the estimation, the number of days when the soil at a depth of 20 cm becomes drier than −49 kPa, decreases in the future as compared to the present time in the summer. However in the future, the number of days increases in the winter due to aridification, which reflects the increase in the amount of evaporation. The number of days when the soil at a depth of 20 cm becomes wetter than −3 kPa, decreases in the future over a year at both fields of Gray Lowland soil and Yellow soil. It was predicted that the fields in Yamaguchi would be drier than present soil water conditions.