To improve the sound insulation, harness insertion property, and formwork removal property of a grommet.

The grommet comprises a small-diameter cylinder part 11 through which a wire harness W/H is tightly penetrated, a first large-diameter cylinder part 13 continued to one end of the small-diameter cylinder part 11, and a second large-diameter cylinder part 14 of which diameter can be contracted continued to one end of the first large-diameter cylinder part 13. A vehicle body locking groove 25 is disposed on the outer peripheral surface on the first large-diameter cylinder part 13, and the second large-diameter cylinder part 14 is provided with a contraction part 17 having thin fold sections 18 on the outer peripheral surface on an opening 15 side with an interval. An annular collar section 20 for sound insulation is projected from the inner peripheral surface of a position close to the first large-diameter cylinder part 13, and an inner-diameter-side tip 20b of the collar section 20 for sound insulation is stuck to the outer peripheral surface of the wire harness W/H. The opening 15 side is wound and fixed by the wire harness W/H and a tape T3 in a state where the thin fold sections 18 are bent to decrease the diameter, and two sealed spaces S3 and S4 for sound absorption partitioned by the collar section 20 for sound insulation are formed in the grommet 10.