PURPOSE: To improve a processing capacity of a drying apparatus without increasing a space for installation and obtain a clear printing color by providing a drying furnace for preheating contiguous to an opening at a forward end of a main drying furnace to preheat metal plates and receiving a forward end portion of a wicket conveyor in the furnace to preheat the wicket conveyor having a large thermal capacity.

CONSTITUTION: A main drying furnace 1 is partitioned into a heating zone 1a and a cooling zone 1b, into which a hot wind or a cold wind is blown out from outlets arranged on an underside of a chamber 11 provided in an upper portion of the furnace. In a combustion chamber 13, air is heated by a burner 9, and simultaneously an organic solvent contained in a circulating air burns. A wicket conveyor 4 conveys metal plates in the furnace while obliquely supporting them by means of wickets 3 provided upright on the endless conveyor. A hot wind type drying furnace 8 for preheating is provided contiguous to a forward end of the main drying furnace 1 in a manner to receive therein a forward end portion of the wicket conveyor 4 and the belt conveyor and to close the forward end of the main drying furnace 1 to heat the forward end portion of the wicket conveyor 4 therein.