Discussed is a glass light guide plate that is used in a back light unit of a display device. Some features of the glass light guide plate for the back light unit can be improved by optimizing a relationship between a direction of a bubble inside the glass light guide plate and a light source, the sizes of the bubble and a light guide pattern, and so on, and by optimizing an arrangement density of light guide patterns in each region, a kind of light guide pattern ink (IR-curable ink), a curing condition, a refractive index, and so on to be suitable for the material of the glass light guide plate.