PURPOSE: To prevent a press roller from vertically moving suddenly by a method wherein when a clamp member passes between an ink feeding roller and press roller, the ink feeding roller is separated from the inner surface of a cylindrical plate cylinder by a first cam, and a distance between the press roller and the axis of the cylindrical plate cylinder is kept uniform by a second cam.

CONSTITUTION: After printing on a printing paper is completed, when a cylindrical plate cylinder 1 rotates further, and a clamp member 18 passes between an ink feeding roller 19 and press roller 35, a first cam following element 2 comes into contact with a cam recessed part 32 of a first cam 28, and a supporting plate 21 ascends by the tensile force of a first spring 21, and the ink feeding roller 19 separates from the clamp member 18. A second cam following element 27 comes into contact with a cam protruding part 33 of a second cam 29 by the tensile force of a second spring 26, and the press roller 35 separates from the clamp member 18 which is located in a flat part 12 on the cylindrical plate cylinder 1, and a distance between the axis of the cylindrical plate cylinder 1 and the axis of the press roller 35 is kept uniform.