Abstract: A reflow soldering device extracts a vaporized component of a contaminative material, such as flux, from exhaust gas from a reflow furnace. The device includes a conveyor for transferring a circuit substrate, a heater for heating the transferred circuit substrate, a cooler for cooling the circuit substrate which has been reflow soldered by heater, discharge pipes and a discharge blower for discharging an exhaust gas at high temperature from the heater to the outside of the device, and a flux remover mounted in the discharge pipes which cools the exhaust gas to 70.degree. C. and below, preferably 60.degree. C. and below, so as to cause a vaporized component, such as flux contained in the exhaust gas, to become liquid or solid and to be removed.