US Patent 10059229 Seat sliding device for vehicle

A rolling element holder holds a rolling element rotatably and slidably. A biasing unit biases the rolling element holder toward a first surface of a fixed rail. A projection is provided on the rolling element holder, and faces a second surface opposite to the first surface. The rolling element holder is configured so that a distance in an up-down direction from a contact point between the rolling element and the first surface to an end portion of the projection on the second surface side becomes larger as the rolling element approaches an end on one side in a slidable range of the rolling element, and so that the projection is brought into contact with the second surface at least when the rolling element is at the end on the one side.