PURPOSE: To solder a printed board in short time despite the size of an IC chip by arranging plural radiation type heat sources with reflection shades and plural hot blast blowers in the cover arranged on the conveyor transferring a printed board.

CONSTITUTION: The plural heat sources 15 having a shade type reflection plate 17 are arranged inside a cover 21 of U shaped cross section, mounted on a freely traveling conveyor 1 arranged at the lower part thereof and the printed circuit board to be transferred is heated. As said heat source 15 a far infrared ray lamp, infrared ray lamp, harogen lamp, etc., are appropriate. Moreover plural duct type hot blast blowers 16 are arranged between said heat sources 15 and the air subjected to a temp. rise to the specified temp. by the heating heater 18 installed therein is blown toward the conveyor 1 from a lower injection nozzle 19. Thereafter this hot blast is exhausted from an upper exhaust duct 8 by an exhaust fan 7 and fed into said blower 16. The printed circuit board can be soldered in a short time.