To produce a press plate to be replaced with a high efficiency by providing a positioning perforating unit, a cutter, and first, second folding units at a downstream side position of a developing unit in the case of partly altering a surface of the plate mounted on a plate cylinder of a printing rotary press.

Two unphotosensed plate materials 12 of sizes corresponding to two pages of newspaper are lithographically processed by an exposure unit 3 via a plate feeder 2. The materials 12 are sent to a developing unit 5 via a plate delivering unit 4, developed, then changed in its direction by a direction changing unit 6, and the materials 2 are perforated at positioning cutouts and holes by a perforater 7. Thereafter, the materials 12 are sent to a first folding unit 9, a folded part for mounting on a plate cylinder of a printing rotary press is formed, and two press plates of a size corresponding to two pages of newspaper are simultaneously manufactured. Then, the materials 12 are cut at a center over a lateral direction, separated into four plate materials of a size corresponding to one page. Thereafter, a folded part for mounting on the cylinder of the press is formed at the plate material by a second folding unit 10, and hence the number of engraving operations can be reduced.