To dispose only one drawer device 30 on the lower surface side of a desk top board 2 for good usability.

The front part of a drawer body 32 which is disposed on the lower surface side of the desk top board 2 so as to be drawn out toward the direction of the front side edge opposing to a user, is provided with an auxiliary housing portion 33 composed of a first auxiliary housing portion 34 including the right and left sides and the center of the front part and a pair of second auxiliary housing portions 35a and 35b which are partitioned by partition walls 36 on the right and left sides of the first auxiliary housing portion 34, respectively, and formed so as to be forwardly protruded. The front end edge 37 of the auxiliary housing portion 33 has a shape protrudingly curved toward the front to the right and left sides across the center part in plan view, like a shape of the front side edge 2b of the desk top board 2. The upper surface of the second auxiliary housing portions 35a and 35b are detachably covered with flat cover bodies 40.