a manufacturing of a printing plate from a thermoplastic porous material comprises a thermal head with a plurality of heater elements, acquire print data of a print pattern including pixel data, with each item of pixel data corresponding to each area of the surface of the porous material partitioned into a lattice shape; identify, print pixel data that is part of the print pattern, and non-print pixel data that is not comprising the print pattern; apply a first heat quantity to a first area corresponding to the non-print pixel data by at least one first heater element, that makes contact with the first area; apply a second heat quantity that is smaller than the first heat quantity to a second area by the second heater element that makes contact with the second area identified by the print pixel data, the second area being where ink readily runs.