PURPOSE: To promote the drying treatment by means of a drying cylinder by sucking the boundary layer of moist air that is formed on the face of the drying fabric with a suction device that is fitted at a distance from the drying fabric.

CONSTITUTION: The suction device 10 is fitted in relation to the drying cylinder K at a distance from the surface of the wire H, which follows the fact of the drying cylinder. When the boundary layer of the moist air is formed on the wire surface, the layer is immediately sucked and removed to improve the drying treatment. The sucking device is followed by the substitution air feeder 11 to introduce the dried and water substitution air instead of the boundary layer of the moist air to promote the drying treatment.