To secure safety by welding a foldingly packing paper by an ultrasonic welding means to lower power consumption while eliminating the residue of heat after the stopping of operation.

This foldingly packing paper welding apparatus 10 is provided with an ultrasonic welding means 20. The ultrasonic welding means 20 is constituted of an ultrasonic oscillator, an ultrasonic vibrator 25, a horns 40 for transmitting ultrasonic waves generated thereby and a foldingly packing paper receiving jig 50. The horn 40 is for ultrasonic resin welding and the tip thereof is so built as to vibrate with a necessary amplitude for the welding of the foldingly packing paper. In the receiving jig 50, a receiving jig structural body 54 is provided on a second receiving plate 53 urged to the side of the horn 40 by compression springs 55a and 55b, a first receiving plate 52 and the like to support the foldingly packing paper between the body and the horn 40. With such an arrangement, the welding of the foldingly packing paper is accomplished by the ultrasonic vibration, hence minimizing power consumption. This eliminates the residue of heat by the stopping of operation eventually removing fear of burn.