PURPOSE: To obtain a novel optical deflector which is capable of electrically controlling a deflection angle.

CONSTITUTION: This optical deflector 1 is constituted by arranging a pair of transparent glass plates 4, 4 provided with transparent electrodes 2 and oriented films 3 on their one-side surfaces so as to face each other and inserting liquid crystals 5 between these glass plates 4, 4. A driving circuit 6 is so connected that an AC voltage or DC voltage is impressed to the transparent electrodes 2, 2. Parallel fringes appear in the liquid crystals 5 when the voltage is applied between the transparent electrodes 2, 2. These parallel fringes function as diffraction gratings. Then, diffracted light appears on an exit side when light is made incident on the optical deflector 1. The light is eventually deflected if the diffracted light is utilized as exit light. The pitch of the parallel fringes changes and the changing of the diffraction angle is possible if the magnitude of the applied voltage is changed and, therefore, the electrical control of the deflection angle is possible.