PURPOSE: To enlarge an upper space of a room by forming a ceiling of a plurality of rectangular frame boards, and moving the frame boards by means of a driving means provided to a rail laid between columns to open the ceiling.

CONSTITUTION: A plurality of rectangular frame boards 25 are combined with each other in tiers to form a ceiling 26, and the frame boards 25 are borne on a rail 24 laid between columns 1 at intervals in the same direction with short sides 27 of the frame foards 25 in a slidable manner. An opening and closing motor 9 provided along the rail 24 is driven to turn right and let wires 20, and the frame boards 25 are moved along the rail 24 to open the ceiling 26. After the ceiling 26 is opened, guide rollers 57 and 58 are provided to sides of an up and down multi-stage storing box 56 arranged to a wall 53 of a room 55, and the storing box 56 is pulled up to the attic 49 with a lifting device of the attic 49 and is stored. Accordingly, floor board area occupied by the storing box can be effectively utilized.