A tabletop elevation adjustment mechanism includes a fixed outer tube, a movable inner tube vertically movable in the fixed outer tube, and a plurality of corrugated sheet members equiangularly fastened to a bottom of the movable inner tube. Each of the corrugated sheet members has a plurality of first and second ridge portions respectively protruding toward two opposite sides thereof. The first ridge portions elastically stopped against an outer surface of the movable inner tube and the second ridge portions elastically stopped against an inner surface of the fixed outer tube.