A cover device for a side sill of a passenger vehicle has a sill cover which includes first and second cover elements which are arranged in a length region of the side sill below a door opening and are coupled moveably to one another and a drive unit via which the cover elements are jointly displaceable between a first functional position and a second functional position. The first cover element is pivotable about a first axis and the second cover element is displaceable about a second axis. The second cover element is mounted so as to pivot about the second axis by a bearing device on the first cover element. The displacement movement of the second cover element relative to the first cover element is positively controlled by a slotted link.