An object of the present invention is to provide a welding system wherein
the positional accuracy of welding and the quality of welding are
improved. The present welding system includes an ultrasonic welder for
welding a plurality of webs W together while carrying the webs W. The
ultrasonic welder includes: an anvil roller 10 including a pair of anvils
11, 12; a first ultrasonic horn 21 and a second ultrasonic horn 22 that
apply vibration energy to the webs W in cooperation with the pair of
anvils 11, 12. The pair of anvils 11, 12 are provided symmetrically with
each other with respect to an axis line O of the anvils roller 10. The
first and second ultrasonic horns 21, 22 apply the vibration energy to
the webs W simultaneously while each of the anvils 11, 12 faces the first
or second ultrasonic horn 21, 22.