The present invention provides an optical modulator that prevents aggregation of shape-anisotropic particles. The optical modulator of the present invention includes: (1) a first substrate and a second substrate that are disposed to face each other; (2) an optical modulation layer disposed between the first substrate and the second substrate; and (3) a vertical alignment film. The optical modulation layer (2) contains: (2A) liquid crystal molecules that have a positive anisotropy of dielectric constant with a value of the anisotropy Δε of 10 or more; and (2B) shape-anisotropic particles each including a core material and a coating layer that is formed of a material containing a fluorine atom and constitutes an outer surface of the shape-anisotropic particles. The first substrate includes a pair of electrodes. The liquid crystal molecules and the shape-anisotropic particles are aligned perpendicular to the first substrate with no voltage applied to the electrodes and are tilted parallel to the first substrate by a transverse electric field generated by application of voltage to the electrodes. The liquid crystal molecules have a surface energy in the range of 27 to 35 mN/m. The vertical alignment film has a surface energy in the range of 30 to 40 mN/m.