Disclosed is one example of a sliding device allowing for reliable sliding of members that close an opening of a fixed rail. The sliding device includes: a fixed rail including an opening arranged in a longitudinal direction of the fixed rail; a movable rail slidable with respect to the fixed rail in a state where at least part of the movable rail is exposed through the opening; a first closure member slidable with respect to the fixed rail and capable of closing at least part of the opening, the first closure member receiving a force from the movable rail to thereby slide; a first engaging portion provided to the first closure member and disengageably engaging with a first engaged portion provided to the movable rail; and a second engaging portion provided to the first closure member and disengageably engaging with a second engaged portion provided to the fixed rail.