Abstract: In a method of manufacturing a bag wherein the side edges of a continuous web of the blank are bonded together to form a flat tubular body, the tubular body is cut along spaced cutting lines to form a plurality of sections each having a length substantially equal to the length of a completed bag and one ends of respective sections are closed, reinforcing members are bonded to the blank with their intermediate portions aligned with the cutting lines and then the blank is cut along the cutting lines together with the reinforcing members to form the sections.