The axial thrust bearing device, in particular for the suspension strut of a motor vehicle, comprises a bottom support cover, a top bearing cover, a rolling bearing axially disposed between said covers, and at least a sealing ring axially bearing against the bottom support cover and adapted to reduce any ingress of foreign matter between said covers.The sealing ring comprises at least one friction lip in contact with the top bearing cover and tending to keep said sealing ring in axial contact with the bottom support cover.