In this study, conservation method that prevents collapse of soil structural remains caused by drying and precipitation of salt by controlling the water potential gradient was examined. At Miyahata site located in Fukushima city, soil boring was performed to estimate the ground structure. In laboratory experiments, some parameters that determined water retention curve and hydraulic conductivity of unsaturated soil were estimated by evaporation method and inverse analysis with HYDRUS-1D. Based on the ground structure and unsaturated hydraulic properties obtained, water movement in vertical direction was simulated by numerical analysis. As a result of numerical analysis, it was revealed that the soil of remains would continue to dry. Then, the changes in water potential gradient caused by timely infiltration were also simulated. As a result, it was revealed that downward gradient of water potential and zero-flux plane could be produced alternately. By repeating infiltration and evaporation in a short span, it was revealed that deterioration of the remains caused by drying and precipitation of salt could be inhibited
