PURPOSE: To continuously perform a preliminary soldering and a finish soldering by temporarily storing molten solder injected from one nozzle.

CONSTITUTION: The molten solder 10 is sent in the arrow B direction in the nozzle 3 by a force feeder 11 in a solder vessel 9 in which the molten solder 10 is stored and injected on both sides from an opening part 3a. The molten solder 10 carried to the upstream side in the base plate carrying direction (the arrow 0 direction) then dropped to an upper chamber 9c along a guide plate 3d and the same action is again repeated by the force feeder 11. The solder carried in the direction of a side plate 18 (the arrow E direction) is stored in a storage vessel 5 temporarily and carried backward to the released nozzle 3 side (the arrow F direction). Namely, the substrate 8 comes into contact with the slow flow of the solder stored in the storage vessel 5 and stable finish soldering due to the running out of the solder is performed.