Vertical movement of support members disposed on both left and right sides of a screen are guided by a pair of left and right fixed rail brackets. A manipulation lever manually operable so as to vertically move the screen and connected to at least one of the pair of support members includes a lever main portion which is rotatably supported on at least one of the pair of rail brackets and is connected to one of the support members, and a grip which is connected to the lever main portion. The grip is connected to the lever main portion such that the grip is operable between a projecting position where the grip projects from the lever main portion and a storage position where the grip is folded toward a lever main portion side.