Abstract: This invention provides an elevation mechanism for an armchair armrest, comprising a T-shaped post, a catch cylinder, an adjustment unit, a reflex plate, a U-shaped block and a resilient spring that are fastened by a plurality of screws. At the center of the T-shaped post is a U-shaped depression, on which are a first screw hole, a cross through hole and a second screw hole spaced from top to bottom. The first screw hole serves to fasten a first screw inserted in a first through aperture on the adjustment unit. The vertical slot of the cross through hole accommodates the insertion of the depressed groove of the adjustment unit. The horizontal slot of the cross through hole accommodates a U-shaped block that goes with the depressed groove. At the center of the adjustment unit is a third screw hole to accommodate and fasten a second screw inserted through the second through hole on the reflex plate.