PURPOSE: To shorten the process by introducing products with various sizes continuously in the machine by a method wherein the size of a product is detected, and a sealing width of right and left sealing parts is automatically adjusted, and the interval for the side finishing rollers, which finish both sides in a flat state is automatically adjusted.

CONSTITUTION: A detecting device 2 sends a detecting signal to a sealing width adjusting mechanism 3 and roller width adjusting mechanism 4 side. Upper and lower roller sealing parts 46, 46 mutually approach or separate by a motor for sealing width 8 at the sealing width adjusting mechanism 3, through a threaded rod 7 and nut shaped members 6, 6, and the sealing width is automatically adjusted. A pair of rollers 21, 21 mutually approach or separate by a motor for roller width 14 at the roller width adjusting mechanism 4, through a threaded rod 17 and nut shaped member 18, and the interval between the rollers 21, 21 is automatically adjusted. Then, an article-to-be-packaged 34 is sealed by a lateral sealing unit 25, and is heated in a heater tunnel, and sealed parts 20 which protrude from both sides are pressed by rollers 21 and finished in a flat state.