To provide a cut-off wall partition device with a valve for arranging the cut-off wall partition device with the valve on a cut-off wall, forming a pumping well to perform the underground water treatment of an excavation ground during excavation work in the wall, and keeping the water levels of the upstream side and the downstream side of the cut-off wall equal after work completion.

Two opposite opening bodies with filters 2 set at the prescribed position of a cut-off wall and abutted on an excavation ground are connected by a communicating pipe with a valve 3 to pass water through the upstream side and the downstream side of the cut-off wall, a water opening part 8 is provided on at least one side of the opening body with the filter, and since it is used for pumping or washing of the hole wall of the underground permeable part or the filter, work for providing the cut-off wall on the underground permeable part can be executed efficiently. In addition, while the cut-off wall is being constructed, a cut-off partition device with a valve 1 is arranged on the cut-off wall before solidification, the opening and closing valve and a water opening part are properly operated after solidification, the opening body with the filter is filled with a void filler, the cut-off partition device with the valve is frozen, and quickly and surely disposed at the prescribed position of the cut-off wall by blocking it with a heat insulator.