In a grommet fitted around a wire harness wired in a vehicle, and mounted in a through hole of a vehicle body panel, a radially outward extending portion is provided on an outer peripheral surface at an end of a small diameter cylinder portion, in which the wire harness is tightly inserted. A large diameter cylinder portion is connected to an outer peripheral end of the radially outward extending portion. An annular stretchable portion is provided at a portion connecting the small diameter cylinder portion to the radially outward extending portion. A step is provided on an inner peripheral surface at a boundary position between the small diameter cylinder portion and the stretchable portion, such that a thickness of the stretchable portion is thinner than a thickness of the small diameter cylinder portion. An annular rib is provided on an outer peripheral surface of the boundary position. Radially extending restoring ribs are provided on a convex side surface of the stretchable portion circumferentially spaced in-between.