An optical unit for a laser processing system includes a laser diode including a plurality of laser emitters which emit laser light, a lens unit including a plurality of lenses, a holding block having a light-transmitting property, and a light-shielding film. The holding block and the laser diode are bonded to each other with a first adhesive, and the lens unit and the holding block are bonded to each other with a second adhesive. The light-shielding film is located between the lens unit and the holding block.