To eliminated the leakage of solder and to reduce the energy loss of ultrasonic vibration.

The first-half part 14b of a resonator 14 is inserted into a through-hole 8b through an incorporating hole 8c from the outside of a solder vessel 1, and a rib of a presser member 11 fitted outward to the rear-half part 14c of the resonator 14 is inserted into the incorporating hole 8c. Further, the resonator 14 is arranged so as not to contact with the through-hole 8b and an aperture 11a, and the supporting part 14a of the resonator 14 is interposed with a receiving part 8 and a presser member 11 by fastening the presser member 11 to the receiving part 8 by a screw 12 to fix the resonator 14 to the solder vessel 1. Further, the resonator 14 is constituted of an ultrasonic horn at the solder vessel 1 side and a fin booster at a vibrator 13 side, and the fin booster is formed with a material having good thermal conductivity, such as aluminum, and the vibrator can thermally be protected by radiating the heat transferred from the solder vessel to the resonator.