In this paper a case study of shiel TBM for a tunnel under the Han river between the Sungsoo-dong, Sungdong-Gu and the Chungdaw-dong, Kangnam-Gu in the Bundang railway. The geological investigation results show that some fractured zones exist locally under the northern boundary of the Han river bed, but the other regions consist mostly of hard rocks of good quality in the tunnel excavation level. Also, a high water pressure of about 5kgf/㎠ and a flash inflow of river water due to old boring holes are expected during tunnel excavation. A EPB shield TBM is selected as a optimal excavation machine for the Han river tunnel considering the geological and site conditions. And now we are executing the shield tunnel construction work successfully.