A drying furnace for use in coating drying in which a hot gas recycling duct for emitting radiation heat is disposed on the inlet zone of a tunnel-like furnace main body and resin-removing ducts are disposed along the ceiling of the inlet zone and the exit zone of the furnace main body respectively, wherein the furnace main body is turned in a U-shaped configuration so that the inlet and the exit thereof are arranged side by side, and the hot gas supplied to the hot gas recycling duct is supplied to each of resin-removing the ducts. Resinous substances can surely be prevented from forming and depositing at both of the inlet and the exit of the furnace and the cleaning work for the resin-removing ducts can be saved.