To confirm a height adjusting movement by raising and lowering raising-lowering levers connected to each other by support levers on which a top plate of a desk can be installed, by on air sprung.

Connecting members 4 are formed by connecting the mutual rear side edges of side plates 2 erected from left and right end parts of a bottom plate 1 by a rear face plate 3, and guide levers 7 are arranged on opposed surfaces of the side plates 2, and raising-lowering levers 8 are held so as to be raised and lowered. Support levers 11 are formed by connecting brackets 9 installed on the upper ends of the raising-lowering levers 8 to each other by a connecting plate 10. Almost central parts of the connecting plate 10 of the support levers 11 and the bottom plate of the connecting members 4 are connected to each other by a upright air spring 14. An assembly formed as a separate body drain a desk is formed by assembling the connecting members 4, the guide levers 7 into which the raising-lowering levers 8 are penetrated and the support levers 11, and a height of a top plate 12 is adjusted by installing leg bodies 5 of the desk and the top plate 12 on this assembly. Therefore, a height adjustment can be confirmed by a condition of the assembly before being formed as a finished product.