Abstract: A machine for successively forming open topped bags from a continuous roll of tubular, gusseted packaging material and for sealing the tops of the bags after they have been filled with objects. A pivotal heat sealing member is driven into engagement with the packaging material to seal the top of one bag, effect a series of perforations below the seal, seal the bottom of the next succeeding bag, and sever the packaging material between the two seals. A cutting member mounted on the rear side of the machine is simultaneously pivoted to cut substantially through the front web and the two folded gussets of the packaging material to form a three-sided opening in the top of the second bag. A roller then advances the sealed bottom portion of the second bag into a support tray with the open top portion in a convenient position for receiving objects. A single motor drives the working components of the machine.