To apply an elevation type top plate to an abutting surface at a proper strength by use of a screw type stepless elevation mechanism as an elevation mechanism for the elevation type top plate, and securely maintain its condition.

This device comprises a combined set of furniture comprising a wagon 1 which can be moved between leg plates 9, 9 of a desk 2 or to the outer side of the leg plate 9, and a desk 2. The wagon 1 comprises an elevation type top plate 5 supported by a screw type stepless elevation mechanism at an upper end of a main body part 3, and the desk 2 comprises an abutting surface 31 at an upper part between both leg plates to which the elevation type top plate 5 of the wagon 1, so the elevation type top plate 5 elevates in the condition where the wagon 1 is installed between both leg plates of the desk 2 to apply the elevation type top plate to the abutting surface of the desk 2.