To make the width of vertical sealing executed by a sealing device at side edges of a tubular film variable for a bag-making/packaging machine by a method wherein adjustment is made to the direction of conveyance wherein the tubular film is conveyed to a vertical sealing device arranged at the periphery of a chute for throwing articles therethrough.

Brackets 33 and 35 rotatively supporting upper and lower pulleys 31 and 32 for a pull-down belt 11 that conveys downward a tubular film f around a chute 7 arranged, extending vertically, are made independent from each other, and steps are formed respectively at the front side of the upper and the lower brackets 33 and 35 and the steps are engaged with each other while a bolt 64 contacting from the downside to a projecting part 62 of the upper bracket 33 is provided at the rear side. As the length of upward projection of the bolt 64 is adjusted, inclination of the upper bracket 33 or the pull-down belt 11 is changed, making an overlap width of an overlapping part f' at edges on both sides of the tubular film f increase or decrease, and thereby the width of vertical sealing executed by a vertical sealing device 9 can be adjusted.