A grommet is provided with a circumferential channel around its outer surface serving to hold an automobile body panel, thereby forming a circumferential channel base and first and second channel walls extending outwardly therefrom. The circumferential channel also forms corresponding first and second circumferential edges at respective outermost portions of the first and second channel walls. Further, the first circumferential edge extends farther outwardly than the second circumferential edge in a radial direction of the grommet, and has a flat edge in the same direction so as to hold the car's body panel. The first and second walls become closer as they extend from the channel base, such that the first circumferential edge overlaps the second circumferential edge in a longitudinal direction of the grommet. Further, the portion of first channel wall facing the second circumferential edge is grooved so as to form a circumferential groove along the second circumferential edge and open towards the channel, whereby the minimum distance between the first and second channel walls can be set to be above a predetermined value. When the outwardly narrowing channel in the grommet has such a configuration, a die used for molding such a grommet can be made highly durable.