An ultrasonic welding machine (10) which joins quickly and in a serial manner the base (91) part of the bags (90) with base (91) to the bag (90) body with one or more work station (10) located on a body (11) and reducing the wastage rate of fire by standardizing production, and it is characterized in that, it comprises; at least one mold (40) providing the surface of the base (91) in a suitable position and providing a surface suitable for ultrasonic welding, by covering the bag (90) body, at least one folding mechanism (30) providing ready for welding operation by overlapping the edges of the base part with the body of the bag (90), at least one upper drive element (21) performing the functions of lowering and lifting said workstation (20) onto the mold (40), at least one control panel (70) for controlling said workstation (20), the folding mechanism (30) and the upper drive element (21)