To obtain an implement to be embedded in concrete, which has great cut-off capacity, facilitates mounting of a water shut off valve and adaptation to various types of sleeves, dispenses with dimensional accuracy, and enhances productivity, yield and cut-off workability.

One end of the sleeve 1, composed of an inorganic material, and one end of a nut member 2, composed of metal, are connected together by means of a connecting ring 3; both the ends are embedded so that the sleeve 1 can be located on the side of a surface of a concrete structure 18 inside the concrete structure 18; a cylindrical cut-off member 4, which is equipped with a water growth agent 5, is mounted in the sleeve 1; and the water shut off valve 6 is mounted at a free end of the sleeve 1.