A backlight unit includes: an LED; a chassis including a bottom plate provided on a side opposite to a light exit side; and a first reflection sheet. The first reflection sheet includes a quadrangular bottom portion extending along the bottom plate, and two raised portions raised from each of two adjacent sides of the quadrangular bottom portion toward the light exit side, a joint provided between two adjacent side edges of the raised portions. The side edge of a first one of the raised portions includes a facing portion facing the side edge of a second one of the raised portions in a direction in which the first one of the raised portions is raised from the quadrangular bottom portion, and the first one of the raised portions and facing portion bulge toward the light exit side to have an arched shape.