To provide a system for writing on a vertical plate accurately with a laser beam even if inclination is present at the installing position of the system.

The inventive system comprises a horizontal lens 2 sustaining the horizontal surface, a laser light source 1 for irradiating the horizontal lens 2 with laser substantially from the vertical direction, a section 3 for reflecting a laser vertical beam corrected accurately to the vertical direction through the horizontal lens 2 toward the horizontal direction, and a section 4 for reflecting a horizontal beam reflected horizontally from the horizontal reflecting section 3 in the perpendicular direction, wherein the vertical reflecting section 4 is turnable about the horizontal axis.