A light source device includes at least one discharge tube, a discharge medium sealed inside the discharge tube, and first and second electrodes for exciting the discharge medium. The first electrode is arranged inside or outside the discharge tube, and the second electrode has a plurality of contact portions at which the second electrode is in contact with an outer surface of the discharge tube. The contact portions are located at different distances from the first electrode and are provided discontinuously. Xenon gas and at least one selected from argon gas and krypton gas are sealed in the discharge tube, in which the xenon gas accounts for 60 vol % to 80 vol %. Thus, it is possible to provide a light source device and a liquid crystal display device that provide light emission with high brightness and excellent brightness distribution and that can be manufactured readily.