This backlight device 12 of the present invention includes: a cold cathode fluorescent tube; a chassis 14 that houses at least the cold cathode fluorescent tube on a front surface 14a1 side of a bottom plate 14a of the chassis; and a circuit substrate 32 having a front surface 32a on which electronic components 38a and 38b are disposed, the front surface 32a facing a rear surface 14a2 of the bottom plate 14a of the chassis 14. The heat generated from the electronic components 38a and 38b circulates towards the chassis 14 with ease, and therefore the heat generated from the electronic components 38a and 38b on the circuit substrate 32 can be effectively dissipated by the bottom plate 14a of the chassis 14.