To transfer a printing element part in an equal size and to obtain a printed image having a clear boundary by engraving printing elements on a surface of a plate cylinder used for an intaglio printing, then nitriding a surface of a base material, and modifying a plate forming surface layer.

A printing element part 12 is formed on a surface of a plate cylinder 10, and a nitrided modifying layer 14 having 1 to 10 μm is formed on its surface layer part. The part 12 of the cylinder 10 holds an initial engraved line shape by this modifying treatment. Thus, even when it is inked, the part 12 is accurately transferred to a printing sheet. Accordingly, printing elements having the same size as those of actual printing element part are transferred to the sheet, and edges of the part 12 are not covered by a film. Hence, a boundary part is extremely clearly transferred. This treatment is conducted by a radical nitriding treatment for 1 to 20 hours in a furnace having a temperature of 200 to 700°C by a plasma nitriding process.