Disclosed is a shielding apparatus for high-depth groundwater well pollution prevention grouting comprising: a shielding portion which is provided on the outer circumferential surface of a grouting casing installed in an excavation hole in the ground and compressed to be in close contact with a hollow wall of the excavation hole; a compression portion which is provided on the outer circumferential surface of the grouting casing and formed to descend toward the shielding portion and brings the shielding portion into close contact with the hollow wall of the excavation hole to guide the excavation hole to be sealed; and a pressure equalization injection tube portion which is connected with the compression portion on the outer circumferential surface of the grouting casing and lowers the compression portion by water pressure generated by supplying water from the outside through a water supply tube.