An optical modulator includes: a ferroelectric substrate in which an input optical waveguide, a pair of branched optical waveguides, and an output optical waveguide are formed; a signal electrode that is formed in a vicinity of at least one of the pair of branched optical waveguides; a first protection member that is attached to an input end of the ferroelectric substrate in which the input optical waveguide is formed; and a second protection member that is attached to an output end of the ferroelectric substrate in which the output optical waveguide is formed. The first protection member and the second protection member have a Mohs hardness that is less than or equal to a Mohs hardness of the ferroelectric substrate, and are formed of a glass material that does not have a pyroelectric effect.