PURPOSE: To provide a plate making function to a printing press per se to obtain an offset printing method and a press improved in printing speed by a method wherein after a non-printing material is applied on the surface of a plate drum by an ink jet recording head on the basis of signals from an image data operation part and dampening water and ink are also applied thereon, the ink is transferred to paper or the like.

CONSTITUTION: Digital image data inputted to an image data operation part from the external is arithmetically processed. With the rotation of a plate drum 1, the surface thereof is made lipophilic all over by a cleaning device 5. The image data is transmitted to an ink jet recording head 2a. A non-printing material is applied to a plate drum 1a correspondingly to a non-printing part thereof. After the non- printing material is dried and set, a printing state is established. A thin film of dampening water is supplied from a dampening water supply device 3 to be several micronmeters thick. Thereafter, ink adheres to a printing part without the dampening water by an ink supply device 4. The ink on the printing part on the surface of the plate drum 1a is transferred onto the surface of a blanket cylinder 6, furthermore being transferred to printing paper to be printed when the printing paper to be fed on an impression cylinder 7 from a paper feeder 8 is passed between the cylinder 7 and the blanket cylinder 6.