To newly form a marginal space for operating a mouse as required by using a wagon desk with a lift top plate arranged between both leg plates of a flat desk to constitute a winged desk or installed on the outside of the leg plate to be utilized as a side desk.

This wagon desk 1 can be installed between both leg plates 10, 10 of a flat desk 2 or on the outside of the leg plate 10, and a lift top plate 6 supported by the support members 14, 14 of a lift mechanism 5 is provided above the fixed top plate 4 of a main body section 3. A plate-like member 15 extractable to this side than the lift top plate 6 is provided between the support members 14, 14 arranged on both sides of the lower face of the lift top plate 6.