PURPOSE: To provide a fine working device capable of producing in short time the ruggedness having sharp edged bottom shape of blade shape, etc., as for a fine working device, which forms ruggedness on the surface of a work to be worked by irradiating on a work to be worked and engraving the surface of a work to be worked through irradiating beam.

CONSTITUTION: Laser beams La, Lb having different wave length are outputted from laser oscillators 21a, 21b, after superimposed at a half mirror 21c, the laser beams irradiate a dry plate 23 through a lens 22. Because of the different wave length laser beams La, Lb, each focus at condensing through the lens 22 is different respectively. By simultaneously irradiating the laser beams La, Lb, the etched hole having sharp edged bottom shape is formed on the dry plate 23, due to the difference of the focus length.