A water cut-off structure includes: a shield electric wire having a braid covering signal lines; an exterior member through which the shield electric wire is inserted; and a grommet that is arranged at an opening of an attachment member, partitions one side and the other side of the attachment member, and has an insertion portion through which the shield electric wire is inserted, an exposed portion where the braid is exposed to the outside is arranged between the insertion portion and the exterior member and is provided with resin that is formed integrally with the exterior member and the insertion portion and is poured into a space between the signal lines in the braid, a space between the braid and the signal lines, a space in the braid, a space between the braid and the exterior member, and a space between the braid and the insertion portion.