A liquid crystal display device characterized in that an illumination unit includes a substantially wedge-shaped light-guiding plate 5 being tilted such that plate thickness becomes thinner from one side edge toward the other side edge, a light source 41 disposed along the thicker plate surface of the light-guiding plate, lead wires 43, 44 of the light source, and a housing 7 that houses these parts, in which the light-guiding plate is installed such that a gap L.sub.2 between the backside 52 of the light-guiding plate and the bottom wall of the housing becomes larger as the plate thickness becomes thinner, and a portion of the lead wires resides in the gap L.sub.2 and the wires are arranged along the other side edge 54 of the light-guiding plate. Further, it is preferable that a circuit board 11 for driving a liquid crystal display panel 2 be attached on the backside of the housing to lie parallel with the liquid crystal display panel and a guide member 7a for guiding connection of a main body side connector to a connector 11a of the circuit board be formed on the housing. With this constitution, a smaller and slimmer liquid crystal display device can be provided where the lead wires are easily arranged, and connection to connectors is highly facilitated.