To provide a desk in which even a top plate of a side cabinet can be utilized as a desktop space and the position in left and right directions of the side cabinet can be changed corresponding to an installation space.

The desk comprises: the top plate 1; a back plate 2 disposed at the rear end of the top plate 1; the side cabinet 4 which is disposed at either left or right side of the lower surface of the top plate 1 and receives the loads of the top plate 1 and the back plate 2; a front guide member 6, a rear guide member 7 and an engaging means 10 constituting an upper surface guide means disposed between the lower surface of the top plate 1 and the upper surface of the side cabinet 4 for guiding the movement in the left and right directions of the side cabinet 4; and oblong hole 19, a female screw 20a and a bolt 20b constituting a rear surface guide means and a fixing means disposed between the front surface of the back plate 2 and the rear surface of the side cabinet 4 for guiding the movement in the left and right directions of the side cabinet 4 and fixing it. The side cabinet 4 is made movable from the side part of the lower surface of the top plate 1 to the side over the side end of the top plate 1.