A photo-driven optical deflecting apparatus in which a light beam is deflected by using only light beam(s), comprising (a) a dielectric substrate having "photovoltaic effect"; (b) one or more first couples of electrodes formed in or on at least a portion of the surface(s) of said substrate so as to polarize the portion(s) positioned between said couple(s) of the electrodes formed thereby; (c) one or more photo-driving or photo-receiving elements provided at least in the polarized portion(s) of the surface of said dielectric substrate, having a polarization direction oriented in one direction, and having photovoltaic effect so as to generate a voltage between said electrodes; (d) a dielectric and transparent prism having "electrooptic effect" through which a light beam to be deflected is passed and deflected, provided on the surface of said substrate, having a second couple of electrodes provided on a couple of the surfaces of the prism, which surfaces are parallel to the optic axis; and a polarizer provided on the surface through which said beam enters; (d) leads electrically connecting said first electrodes to said second electrodes; the light beam to be deflected enters through said polarizer into said prism through which the light beam passes to be deflected; and said prism being operated directly by the photovoltage generated by said photo-driving element(s).