To prevent clogging in a jet nozzle without using any inert gas and to allow reliability to be improved by filling a through hole of a printed circuit board with the molten solder.By flowing the molten solder 4 in the solder bath 2 from inside of the inner cylinder 15 to a nozzle cap 19, the inside of the nozzle cap 19 is filled with the molten solder 4, and the molten solder 4 filling the inside of the nozzle cap 19 is flown downward from between an inner cylinder 15 and an outer cylinder 16 without substantially flowing it to outside from an insert hole 19a. This enables the molten solder 4 to be prevented from oxidizing because the molten solder 4 is not exposed to the outside air. For this reason, it is possible to prevent clogging in the jet nozzle 3 without filling a part of nozzle outlet with any inert gas as in the conventional soldering apparatus. Further, since the soldering is performed with a lead 31 of electronic component 30 being inserted into the insert hole 19a, it is possible to fill the through hole of the printed circuit board P with the molten solder 4, so that the reliability can be improved.