An object of the present invention is to realize the suppression of uneven brightness at low cost in a lighting device. A backlight unit 12 according to the present invention includes: LEDs 17 as a light source; a chassis 14 including a bottom plate 14a disposed on a side opposite to a light output side with respect to the LEDs 17 and housing the LEDs 17; and a first reflection sheet 22 reflecting light including a square-shaped bottom portion 24 disposed along the bottom plate 14a, and at least two rising portions 25 and 26 rising from at least two adjacent sides of the bottom portion 24 toward the light output side such that a seam J is formed between adjacent side edges 25a and 26a. An overhang portion 28 is formed on the side edge 25a of the first rising portion 25 of the at least two rising portions 25 and 26. The overhang portion 28 overhangs beyond the seam J in a direction from the bottom portion 24 to the second rising portion 26.