Abstract: In a lateral sealer device for a vertical packaging machine, a strip of film is wound in a cylindrical form around the outer circumferential surface of a supply pipe by a film former, to form a bag-like package, both side edges of the resultant film are overlapped and heat-bonded together, and the bag-like package of film is then heat-bonded laterally at a predetermined pitch. In this sealer device, a sealer frame, which is provided with a pair of lateral sealer members which can toward and away from each other, is attached rotatably to a main frame of a packaging machine. The sealer frame is turned to a desired angle according to the packaging mode being employed and is fixed at a suitably-selected position, so that lateral heat-bonding of packages made of a strip of film can be done in a desired manner.