PURPOSE: To enable printing density to be improved by increasing a discharge amount by increasing an ink retention quantity of a micropore two times by a method wherein parts of a ring-shaped film prepared by connecting both ends of a perforated film are stuck fast to each other by super-imposing, and the close stuck part is heated with a thermal head.

CONSTITUTION: A perforated film 2 is made into a ring-shaped one by connecting its both ends, and parts in contact with a thermal head 1 are stuck fast to each other by being superimposed. Further, the thermal head 1 comes in contact with the superimposed close stuck parts of the film 2, Ink in a micropore 2a of the film 2 is suddenly heated to generate transformation in a phase. The ink is discharged from the micropore 2a by pressure with a generated bubble and stuck to recording paper 6 to perform printing. Therefore, since a depth of the micropore 2a of a part wherein the thermal head 1 exists is two times a thickness (t) of the film 2, retention of a necessary ink quantity becomes capable of being realized.