PURPOSE: To provide the liquid crystal display device which performs superior display illumination without optical interference such as moire fringes when a light guide plate with lenses which is high in light utilization efficiency, is used.

CONSTITUTION: The light guide plate 2 having striped lens parts arrayed on the front or back surface is arranged on the back surface of a liquid crystal cell 1 which has orthogonally arranged electrodes. A light source 3 is arranged on the side of the light guide plate 2. As the 1st example, the ridge lines 21 of the striped lens parts of the light guide plate 2 are arranged crossing the electrodes 11 of the liquid crystal cell slantingly. As the 2nd example, the pitch of the striped lens parts of the light guide plate is made smaller than the electrode pitch.