To provide an elevating/sinking mechanism of a simplified configuration which can accomplish smooth motions.

Objects to be elevated and sunk 8 and 11-15 including a liquid crystal display DP to be elevated and sunk through a hole or notch formed in the top plate 1 of a desk or table and a supporting member 8 such as a frame to support the display DP are accommodated below the top plate 1 from the hole 7 or notch, linear guide members 9 and 10 to support slidably the left and right ends of a beam member 13 on which the objects 8 and 11-15 are placed, are installed under the top plate 1 positioned outside the left-right width of the objects 8 and 11-15 and generating approx. evenness fore and aft and to the left and right about the center of gravity of the objects 8 and 11-15. To the beam member 13, reaction force members 14 and 15 are coupled which act a force opposing to the load generated by the objects 8 and 11-15.