A backlight device 10 wherein a light source 13 and a light guide plate 12 for introducing light components from the light source 13 from the incident surface 12a provided on an end surface to emit the light from the surface 12b are included, a plurality of the wedge-shaped grooves 12e are formed on the surface 12b of the light guide plate 12 in stripes in plan view, and micro-irregularities 12g are formed between adjacent wedge-shaped grooves 12e is disclosed. A liquid crystal display device 1 having the backlight device 10 formed on the back surface of the liquid crystal display unit 20 is disclosed.