A table leg includes a fixed outer tube, a movable inner tube vertically movable in the fixed outer tube and having two pairs of parallel walls, and a plurality of rotating members rotatably mounted to one pair of the parallel walls of the movable inner tube and partially protruding out from an outer surface of the movable inner tube and stopped against an inner surface of the fixed outer tube, such that the rotating members are rotatable when the movable inner tube is moved relative to the fixed outer tube.