PURPOSE: To eliminate the imperfect soldering occuring in foam in a solder tank which gushes a solder melt from a gushing tank and solders a printed circuit board with electronic parts traveling above the tank by providing a specifically a gushing body in the gushing port of the gushing tank.

CONSTITUTION: Solder melts 6, 7 in primary and secondary tanks 4, 5 are respectively pressed by driving of motors so as to enter the inside of gushing tanks 8, 9 and arrive at gushing ports 10, 11. The melt 6 arrives at a circular cylindrical gushing body 12 having an engaging part 12a engaging slidably with a guide part 10a formed in the longitudinal direction of the port 10. The melt gushes upward from many through-holes 13A, 13B formed zigzag with the deviation from each other in the position on the front and rear in the traveling direction A of a printed circuit board 1 from the vertical centerline. Then the liquid 6 flows forward and backward in the direction A and forms many rugged waves 6c, 6d together with gushing waves 6a, 6b. The body 12 is moved back and forth by a crank device 14 at the same time to repeat the reciprocating motion in the direction B. Then the waves 6c, 6d repeat the reciprocating motion in the direction B as well.