To improve the reliability of a grommet in terms of waterproofing property, to prevent deformation in one small-diameter cylindrical portion from spreading to other small-diameter cylindrical portions, and to promote reduction in the size of the grommet and the enhancement of wire insertion workability.

The grommet 10 is so designed that it is fit onto a group of electric wires W1 to W3 and attached into a through-hole H formed in a floor panel P. The grommet 10 comprises a large-diameter cylindrical portion 11, which is fit into a through hole H in a floor panel P and has a closed portion 11a at one end; a panel anchoring portion 17, provided on the periphery of the large-diameter cylindrical portion 11 at the open other end 18; and a plurality of the small-diameter cylindrical portions 12 to 14 so formed that they are connected from the closed portion 11a to the hollow portion inside the large-diameter cylindrical portion 11. The grommet is provided with a recessed portion 15, which is formed at the base of each small-diameter cylindrical portions 12 to 14 and is extended throughout the circumferences of the small-diameter cylindrical portions.