Disclosed are a back light assembly for preventing discoloration and deformation caused by heat generated from a lamp, and a liquid crystal display device for displaying an enhanced image. The back light assembly includes a receiving container, a lamp, a glass substrate and a diffuser. The receiving container has a receiving space. The lamp for generating the light is disposed in the receiving space. The glass substrate is interposed between the liquid crystal display panel and the lamp. The diffuser diffuses the light generated by the lamp so as to unify a luminance distribution of the liquid crystal display panel. The liquid crystal display device includes the back light assembly.