PURPOSE: To enhance the quality of printed matter by faithfully transferring ink according to a pattern to a blanket cylinder, by providing air pipes having at least one of plural blow ports and suction ports opened toward the blanket cylinder in the peripheral surface direction thereof on the downstream side in the cylinder rotary direction of each plate cylinder and the blanket cylinder at the opposed contact point of both cylinders.

CONSTITUTION: Air pipes 23 are respectively supported on the downstream rotary direction of the plate cylinders 11, 12 of a printing unit 2 and a large number of blow ports 24 are opened to each of the air pipes 23 toward the peripheral surfaces of both cylinders 9, 10. In printing work, the ink of an image line part is transferred to rubber impression cylinders 9, 10 from the plate cylinders 11, 12 and, at the same time, a part of the water of a non-image line part is transferred thereto. The water transferred goes to the opposed contact point of the plate cylinders 11, 12 on the downstream side of cylinder rotation, but since the air injected from the blow ports of the air pipes 23 are blown to the downstream sides of the plate cylinders 11, 12, the water adhered to the peripheral surface of both cylinders 9, 10 is dried and blown off and the quantity of water going to the plate cylinders 11, 12 on the downstream side becomes min. and the pattern on the surface of a plate is faithfully transferred to paper without irregularity.