A light guide panel includes a top surface configured to have first and second sides extending in X- and Y-axis directions, respectively, a bottom surface configured to be disposed opposite to the top surface, and includes a base surface, and a plurality of diffusion patterns which is provided to protrude from, or to be recessed into, the base surface, and each of the plurality of diffusion patterns including a first inclined surface which defines a first inclination angle with the base surface and a second inclined surface which adjoins the first inclined surface and defines a second inclination angle with the base surface, and a first side surface and a second side surface configured to be disposed between the top surface and the bottom surface and face each other, where the first inclination angle ranges from about 1.8 degrees to about 5.7 degrees.