A backlight unit includes a light source portion configured to provide light to a display panel, a reflection sheet arranged on a lower part of the light source portion, a mold frame accommodating the light source portion, and a support frame which supports the mold frame and includes a bottom portion, first and second side wall portions which extend upward from both end sides of the bottom portion and face each other, a ceiling portion which extends in a horizontal direction from an upper end of the first side wall portion, and a slant portion slanted downward from an end part of the ceiling portion and having one end that comes in contact with the end part of the ceiling portion and the other end that comes in contact with an upper end of the second side wall portion.