Abstract: An armchair body which can be dismantled composed of (1) a first one-piece rigid plastic unit including a base serving as a seat, a base of a seatback extending upward from the seat, and two opposed arms extending upward from the seat, and (2) a second one-piece unit which serves as an upper part of the seatback and which is detachably attachable to the first one-piece unit. The base of the seatback and the two arms at their upper surface are present substantially in a common plane. This upper surface contains therein integral alignment and anchorage elements structured to cooperate with mating alignment and anchorage elements present as an integral part of the lower portion of the second one-piece unit.