It is an object of the invention to provide a light modulator using a thin plate having a thickness of 20 μm or less and capable of stably holding a conductive film suppressing troubles such as resonance phenomenon of microwaves in a substrate and pyro-electric phenomenon and to provide a method of fabricating the light modulator. The light modulator includes: a thin plate (10) formed of a material having an electro-optic effect and having a thickness of 20 μm or less; a light waveguide (11) formed on the front or rear surface of the thin plate; and modulation electrodes (13, 14) formed on the front surface of the thin plate to modulate light passing through the light waveguide. The light modulator further includes a reinforcing plate (16) bonded to the rear surface of the thin plate and a conductive film (17) continuously formed in the range from the side surface of the thin plate to the side surface of the reinforcing plate.