An object of the present invention is to reduce its tendency to generate local deformation in an extending member of a backlight unit. A backlight unit 12 according to the present invention includes LEDs 17 as light sources, a chassis 14 storing the LEDs 17, a reflection sheet 21 and an LED substrate 18 that are extending members along an inner surface of the chassis 14, a holding member 20 fixed to the chassis 14 and holding the reflection sheet 21 and the LED substrate 18 with the chassis 14 such that the reflection sheet 21 and the LED substrate 18 are sandwiched between the holding member 20 and the chassis 14, and a restricting part 26 restricting positional relationship of the holding member 20 with respect to the reflection sheet 21 and the LED substrate 18 such that a gap C is provided between the holding member 20 and the reflection sheet 21.