A backlight unit prevents the display quality degradation of a LCD device and improves the long-term reliability thereof. The unit comprises at least one fluorescent lamp having a first end and a second end; a first cable or wire connected to the first end of the lamp; and a second cable or wire connected to the second end of the lamp. The first cable or wire is different in shape or type from the second cable or wire. A conductor of the first cable or wire is approximately equal in cross-sectional area to that of the second cable or wire. When two or more fluorescent lamps are used, a cross-sectional area of the conductor of the first cable connected commonly to the first ends of the lamps is approximately equal to the sum of cross-sectional areas of the conductors of the second cables or wires connected respectively to the second ends thereof.