PURPOSE: To correct a circuit board without requiring a reheater by assembling a correcting part which corrects the circuit board to the rear part of a reflow furnace body.

CONSTITUTION: The reflow furnace heats the circuit board 7 to a for example, temp. in the reflow furnace body 2 and solders the same. The circuit board 7 after the soldering is moved by the movement of a conveyor 10 to the correcting part 8. The circuit board 7 which does not require the correction is sent as it is to the ensuing stage. A perforated supporting means 11 is raised by the rising effect of a lifting means 12 and the circuit board 7 is supported by the tips of respective supporting pins 22b and is raised when the circuit board 7 which require the correction is sent to the correcting part 8. This circuit board 7 is parted from a conveyor 11 and is brought near to a heater 14 side. Hot air of the temp. below the thermal deformation temp. of the circuit board 7 is blown to the circuit board 7 by the effect of the heater 14 and a fan 15 in this state and while the circuit board 7 is slowly cooled, the circuit board is naturally corrected flat on the supporting pins 11b having a uniform height. the lifting means 12 is moved by the effect of a timer, etc., and the supporting means 11 is lowered, by which the circuit board 7 is returned onto the conveyor 10 and is sent to the ensuing stage.