To provide a drying technique which can reduce an excessive calorific value that has been supplied to an area that is easily heated in a dried object.

In a drying furnace, during a time period Ta shown in Fig.3(b), radiant heat emitted from a heating means is supplied to a side sill of a vehicle body. The temperature of the side sill is surely approximated to the temperature of a door outer panel of the vehicle body by supplying the radiant heat to the side sill. With this way, since the side sill is heated substantially in the same manner as the door outer panel without supplying excessive heat to the door outer panel. Therefore, the technique which can reduce the excessive calorific value that has been supplied to the door outer panel, the area that is easily heated in the dried object.