To provide a cabinet desk whose loading area can be widely varied and whose movable top plate has a high loading capacity.

A cabinet desk 10 incluses a fixed top plate 14 supported at a specified level from a floor. A movable top plate 28 is contained at an almost superposed position with the fixed top plate 14, while it is not used and it is almost horizontally drawn to this side in the depth direction of the fixed top plate 14 when it is used. A first guide rail and a first guide roller work as retaining means to hold the depth side in the depth direction of the movable top plate 28. This side in the depth direction of the movable top plate 28 is supported on the floor face by supporting members 34 whose one end is brought into contact with the floor face and whose other end is fixed to the movable top plate 28.