By supplying wire solder with slight warmth, flux explosion and a soldering tip temp. fall are suppressed. By warming wire solder at about 100 degrees C beforehand, the rapid temperature rise at the time of wire solder being supplied to the tip is suppressed, flux explosion is prevented, and scattering of a solder ball or flux is controlled. By warming lead-free soldering beforehand and supplying it, the temperature fall of the soldering tip is prevented and it contributes to the stability of soldering quality.   *A temperature controller is included as a set.