To carry out the operation function of forming perforation cuts and portion pack bags of respective required numbers each time on the same site by using a portion pack sealing section and a cutter and separating a perforation cut operation section on a pack device forming section.

An outer paper press member 3 and an inner paper press member 7 movable by the given distance across a packaging paper moving line C are provided facing each other, and a cutter 10 positioned inside the inner paper press member 7 and moved forward and backward together with the paper press member 7 to clamp the packaging bag and then moved by the adequate distance to form the perforation and moved more than the time of formation of perforation to cut the portion bag is provided. The device is also provided with a cam mechanism having a cutter 10 for cutting the portion packs by moving the cutter more than the distance when the perforation is formed and moving forward and backward relatively the paper press members 3 and 7 by the external power, a cam mechanism for moving forward the cutter 10 by the required distance at the point of timing of clamping the bags to be packaged by the paper press member 7 and the outer paper press member 3 facing each other from the inside of the paper press member 3 and forming the perforation and a cutting amount varying cam mechanism 30 for selecting either the formation of perforation or the cutting when the cutter 10 is moved forward.