When a grommet provided with a wire insertion tubular portion is mounted in a through-hole of a vehicle body panel by engaging a vehicle body engagement recess on an outer periphery of the grommet with a peripheral edge of the through-hole, the present invention prevents the wire insertion tubular portion from being caught by the peripheral edge of the through-hole, bending toward the vehicle body engagement recess side, and being wedged in between the peripheral edge of the through-hole and the vehicle body engagement recess, and thus enables the grommet to be securely mounted in the through-hole. A rib is provided between an outer peripheral surface on a central axis line side of a wire insertion tubular portion and a peripheral wall of a central tubular portion in order to reinforce a base on the central axis line side of the wire insertion tubular portion.