The optical deflector comprises: an optical waveguide 12 of a dielectric material having electrooptical effect; and a pair of electrodes 10, 14 opposed to each other across the optical waveguide, an electric field is applied between the opposed electrodes to change a refractive index of the dielectric material to thereby control a propagating direction of signal light propagating in the optical waveguide 12, wherein the dielectric material has a first refractive index in its initial state, has a second refractive index by application of an electric field of a first polarity, and retains as a third refractive index a refractive index obtained after the electric field has been removed. The dielectric material has the third refractive index has the first refractive index by the application of an electric field of a second polarity different from the first polarity and removal of the electric field.