PURPOSE: To simplify the driving mechanism of a sealer by a method wherein a cross sealer and longitudinal sealer, including preliminary sealer are operated by respective pairs of ascending rods and descending rods which are horizontal and move vertically by rocking of rocking levers which are pivotally attached to rocking/driving shafts.

CONSTITUTION: For a packaging continuous body 10, a longitudinal side part is preliminarily sealed by a preliminary sealer 9, and then the top edge and bottom edge are sealed by a cross sealer 13, and both longitudinal side parts are sealed by a longitudinal sealer 14. That is, by timing of seals, 2 pairs of rocking levers 43 rock by rotating of 2 pairs of rocking/driving shafts 44 by a specified angle, and a pair of ascending rods 41 ascend, and a pair of descending rods 40 descend. For this reason, respective lower side seal members 32, 52, 62 of the preliminary sealer 9, cross sealer 13 and longitudinal sealer 14, which are supported on the ascending rods 41 by elevating rods 36, 56 66, ascend, and respective upper side seal members 31, 51, 61 of the preliminary sealer 9, cross sealer 13 and longitudinal sealer 14, which are supported on the descending rods 40 by elevating rods 33, 53, 63, descend to perform respective seals.