A light guide plate and a liquid crystal display device having the same. The light guide plate is disposed upstream of a liquid crystal panel to refract light supplied through an edge thereof, toward the liquid crystal panel. In the light guide plate, a plate body is disposed at a side of a light source for supplying light when a supply voltage is applied. A plurality of pyramidal diffusing elements are arrayed in a predetermined pattern on a surface of the plate body. Each of the diffusing elements is rotated clockwise or counterclockwise about an axis extending through a vertex of the diffusing element perpendicularly to the surface of the plate body so that an edge of the diffusing element facing a reference line connecting a central point of the light source to a central point of the plate body is angled 10.degree. to 35.degree. about the reference line.