Recently, owing to the change of industrial structure and living style, consumption of water resources has changed. In this study, we propose the method to estimate the pumping up rate of groundwater and apply this proposed method to the confined aquifer of Yatsushiro area.The estimation of the pumping up rate of groundwater by hearing investigation to all family units is the most reliable method. But that needs a lot of work and time. So it is realistic to identify the pumping up rate by utilization of observed groundwater levels. At first, we break up several areas from the land use map and give the pumping up rate to each area and make the pumping up rate pattern. Next, we identify the pumping up rate pattern by genetic algorithm to minimum the difference between observed and calculated groundwater levels. We study this method and could get annual change of pumping up rate of groundwater.