Abstract: Provided is a swing-driving device for driving two low molding units so as to swing around corresponding swinging fulcrums, each of the blow molding units having a carriage, one end portion of which is supported by the swinging fulcrum so as to swing, and a blow molding mold disposed on the carriage. The blow molding mold of one blow molding unit receives a parison on a common receiving position and is made to be an mold close state. The blow molding mold swings around a swinging fulcrum, and moves from the receiving position to a shunting position via a detaching position. Thereafter, the blow molding mold returns to the detaching position and is made to be a mold open state. A hollow article formed by blow-molding the parison in the blow molding mold is take out and moved to the receiving position kept in the mold open state.