To realize the miniaturization and the weight reduction for the whole of a semi-automatic packing machine in such a manner that a tightening roll for a band and a band feeding/pulling-back roll are made into a unit driven by reducing a shared motor, and in addition, and facilitate the assembly and the adjustment work by fixing the unit to the extension section of a sealer unit attaching plate.

In this band driving device, the driving shaft 8 of the feeding/pulling-back roll 7A and the driving shaft 10 of the tightening roll 9A are projected in parallel from the attaching surface of a reduction gear directly connected with the motor M1. Then, the attaching surface 12A of a reduction gear case 12 is fixed by sharing sealer unit attaching boards 20 and 21.