PURPOSE: To improve the quality of a joining part by forming the pumping container of a solder in U pipe shape and providing the difference in the heights at upward both ends of container thereof.

CONSTITUTION: A solder pumping up container 2 is formed in U pipe shape and a difference in the height of the upward facing both ends 2a and 2b in U pipe shape is provided. After removing the oxide on the upper face of the solder 3 inside a solder tank 1 by a scraper a solder 3 is filled up in the container 2 by sinking the container 2 in the solder 3. A soldering is then performed by lifting the container 2 and a soldering joining part is dipped in the pipe port 2c of lower part. In this case, the oxide unable to be removed by the scraper and that existed on the upper face of the 1st pipe port 2c are completely removed. The quality of the joining part is thus improved because of impurities being eliminated on the solder joining part.