A backlight unit 12 includes LEDs 16, a first light guide plate 18A, a second light guide plate 18B and a fitting structure. Each of the first light guide plate 18A and the second light guide plate 18B has a light entrance surface 34 and a light exit surface 36. The light entrance surface 34 faces the corresponding LED 16 and light from the LED 16 enters through the light entrance surface 34. The light exit surface 36 through which light exits is arranged along an arrangement direction in which the LED 16 and the light entrance surface 34 are arranged. The light guide plates 18 are arranged in a parallel layout in the arrangement direction and partially overlap in a direction perpendicular to the light exit surface 36. A light exit portion 31 is an overlapping area OA that is provided on the first light guide plate 18A on a relatively light output side. A fitting structure restricts relative movement of the light exit portion 31 toward the light output side with respect to the second light guide plate 18B provided on a side relatively opposite to the light output side. Accordingly, uneven brightness is less likely to occur.