To provide a construction method for lowering underground water level for reducing cost of facility and man-hours of work.

In this construction method, an open soil retaining wall 2 is constructed between a construction zone and an excavation zone , an impervious soil retaining wall 4 is constructed around the excavation zone except a face adjacent to the construction zone , and an impervious soil retaining wall 5 is constructed around the construction zone except a face adjacent to the excavation zone . Then, the excavation zone is excavated to form a shaft S. A sump 6 is digged on a bottom face of the shaft S to install a pump 7, and drain holes D2-D4 are formed on the open soil retaining wall 2 from an excavation zone side. Consequently, the underground water sunk into sandy soil in the construction zone is drained into the shaft S through the drain holes D2-D4 by flowing down naturally, thereby reducing an underground water level in the construction zone . The underground water in the construction zone drained into the shaft S flows into the sump 6, is pumped by the pump 7, and is drained to the outside of the excavation zone .