PURPOSE: To perform soldering in an irreducible minimum necessary heating time, and to reduce thermal influence upon parts by heating a chip where parts terminals are pressed onto terminals supplied with solder and flux through a heat supply block.

CONSTITUTION: A heater 10 is turned on to heat and hold a heat supply block 12 at set temperature through a heating block 11. Further, a chip holder 8 and a heat chip 7 of good thermal conductivity where low-fusion-point metal and flux are hard to stick are arranged at distant from a flank of a heat supply block 12. On a substrate terminal 2 distant from a flank of the heat chip 8, solder 3 and flux 4 are supplied and after a parts terminal 6 is arranged on it, the heat chip 7 is lowered to press the terminal. Then, the heat supply block 12 is lowered to be pressed against the top of the heat chip 7 and after a specified time passes, the heat supply block 12 is separated from the heat chip 7. Further, after a specified time passes, the heat chip 7 is separated from a terminal 6, and terminals 2 and 6 are soldered.