To provide an attachment for a desk in which a wide space above a top plate can be used, the maneuverability of the desk can be extremely improved with good appearance and a wiring treatment such as a power supply cord or a modular cable or a maintenance work can be easily carried out.

An attachment for a desk comprises a base part 1 having a bottom part fixed to the top surface of the desk and an inner space 1a opened upward and a main body part 3 connected to the base part 1 through a hinge part 2 so as to pivotally rotate upward and downward so that the inner space 1a is openable, and having receptacles embedded in one end side of the upper part. On the upper part of the main body 3, a housing part 3b opened upward is provided. At both upper edges of the housing part 3b, guide grooves 3c and 3d are respectively formed. A slider shaped base part or a band 9 as means for operating a personal computer is slidingly fitted into both the guide grooves.