PURPOSE: To form a highly precise opening while reducing the processing cost by a means of causing no environmental pollution by printing cream solder to a specific position on a printed writing board through the opening formed in a plastic plate by a processing means comprising an excimer laser and the like.

CONSTITUTION: The outside of a screen 2 made of a polyester is supported on a printing frame 1 of a square pipe made of aluminum, and a plastic plate 4 which is the main part of a printing mask is mounted to the inside of the screen 2 via an adhesive joint 3. The plastic plate which is used as the printing mask has an opening formed by utilizing abrasion processing by an excimer laser. In the concrete terms, laser beams outputted from an excimer laser oscillator main body are irradiated on the plastic plate via a projection lens through a shielding aperture mask having a specific shape, whereby the opening having the specific shape is formed. Cream solder can be accurately supplied onto a pat of a printed wiring board through the opening, and printing at a minute pitch can be performed.