A trim element includes a support comprising a groove delimited by a first wall and a second wall, and a first covering layer having at least one edge received in the groove. The trim element further includes a retention device for retaining the edge of the first covering layer in the groove, the retention device having a supporting element extending at least partly into the groove and applying a part of the outer face of the edge of the first covering layer against the second wall of the groove, with the first covering layer covering the groove from the first wall to the second wall.