It is not uncommon that private wells and small streams are used for daily life in the regions where mountain tunnels are located. Then serious social problems such as well water level fall, being attributable to tunnel excavation can occur. In the design stage, firstly we evaluated that the quantity of leakage water into tunnels. And groundwater drawdown area was simulated using numerical modeling such as MODFLOW to reduce adverse effects on life environment around tunnel. In addition we also used hydrological method to evaluate the groundwater change of tunnel area.