To provide a license-plate mounting structure capable of effectively improving its appearance on a bumper.

A bumper 11 is formed at its license-plate fitting portion 12 with an opening 13, to which a license plate 10 is fixed. A bumper cover 11a is formed with a rib and an interposition member adapted to be inserted into the rib. A boss 16 is projected from a proper end portion of the interposition member, and a hole into which the boss 16 is fitted is formed in the flange part of the bumper cover 11a at a position near the opening 13. The interposition member is fixed at its top face of the bumper cover 11a. The provision of the interposition member as an individual part around the license plate 10 prevents the license plate 10 from being found blackish at its circumference to thereby improve its appearance.