In order to provide a desk in which a component can be commonly used for top plates of various different specifications, the desk is so constructed that a frame 2 which supports a top plate 3 comprises a plurality of frame members 21, 22, 23 and at least a part of the frame members 21, 22, 23 are provided with rail grooves 21a, 22a, 23a as a longitudinally continuous mounting portion and a certain position of the rail grooves 21a, 22a, 23a is selected, and a mounting member 4 through 7 for mounting a component such as optional components or a top plate 3 can be held at the position.