Provided is an optical processing device including: a beam emission portion which comprises a plurality of optical fibers; a plurality of collimating lenses to which a beam emitted from the optical fibers are incident; a dispersion element which disperses the beam emitted from one optical fiber among the plurality of optical fibers; and an optical path conversion optical system which converts an optical path of the beam passing through the dispersion element and allows the beam to be incident to another optical fiber among the plurality of optical fibers, wherein the plurality of collimating lenses is installed in series in the optical path direction of the beam emitted from the optical fiber, and wherein a distance between at least two collimating lenses are adjustable in the optical path direction.