The backlight device 24 according to the present invention is provided with: an LED substrate 30; an LED light source 28; a light guide plate 20 having a light entrance surface 20a on a side surface; a chassis 22 having a bottom plate and a side plate; and spacer members that regulate the distance between the side plate and the light guide plate 20. The side plate has three first side plates 22c and 22d on the surface of which an LED substrate 30 is arranged, and one second side plate 22b on the surface of which the LED substrate 30 is not arranged. The spacer members have an elastic spacer member 34a and a non-elastic spacer member 34b. The space between the first side plate 22c that is opposite the second side plate 22b, across the light guide plate 20, and the light guide plate 20 is regulated by the non-elastic spacer member 34b. The space between the other side plates 22b and 22d and the light guide plate 20 is regulated by the elastic spacer member 34a.