To easily cope with not only a partial change, but a total change of imprints in a short time by inputting information of an imprint pattern, forming a plate of the input imprint pattern on a not formed part of a plate- making paper ribbon, and positioning the formed part of the plate-making paper ribbon at a seal position.

Information on an imprint pattern is input from a key input part 2. A long plate-making paper ribbon 6 comprises a base layer where ink permeates and a coat layer which is set at one face of the base layer and formed of material repelling ink. One or a plurality of imprint patterns determined directly or indirectly from the input information are formed on not yet formed parts through a printing operation on the plate-making paper ribbon 6 in accordance with an instruction from an electric instruction part 5. A local position of the coat layer corresponding to the imprint patterns is removed. An ink pad 1 contains a seal ink and supplies the ink onto the plate-making paper ribbon 6 when a seal pressure is applied. A part of the plate-making paper ribbon 6 where any of the imprint patterns is formed is positioned at a seal position.