A display device includes a light source which generates light, a light guide plate including a first surface receiving the light, and a second surface emitting the light, an optical sheet disposed on the light guide plate and including a sheet body and a sheet guide unit, a mold frame including a guide mold, and a side-surface mold which is extended upwards from the guide mold and in which a recess groove accommodating the sheet guide unit is defined, and a protrusion body including a first end portion inserted in the mold frame, and a second end portion coupled to the sheet guide unit, where an inserting groove in which the protrusion body is inserted is defined in the side-surface mold, and the protrusion body has a smaller width compared to a width of the inserting groove.