The present invention relates to an lighting device capable of reducing UGR (Unified Glare Rating) characterized by comprising the frame portion formed at the peripheral area in which the printed circuit board mounted with a light source and the light source are arranged, and the inserting portion into which the diffusing plate and the optical plate are inserted at the inside of the frame portion simultaneously. Particularly, an air gap can be formed on the closed adhered surface of the optical plate and the diffusing plate.