To provide a coating apparatus of a printing machine capable of preventing the quality of printing from being deteriorated caused by transferring the ink on a coater plate cylinder, and the coater plate cylinder and the printing surface of a flat sheet from being scratched, in a case of a printing job without coating with a varnish in the printing machine equipped with the coating apparatus.

To achieve the purpose, the coating apparatus has such a constitution that a silicon plate 20 is attached windingly on the coater plate cylinder 11, to prevent the ink from transferring on the coater plate cylinder 11 by utilizing repulsive property between silicon and a waterless printing ink. In addition, it has such a constitution that the ink is prevented from transferring on the coater plate cylinder 11 by pressing the coater plate cylinder 11 attached wound with a silicon plate 20 on a coater impression cylinder 10 conveying the flat sheet S to increase a binding force between the ink and the flat sheet S.