PROBLEM TO BE SOLVED: To provide an optical modulator and the like that have no phase deviations between two polarized waves of polarization-multiplexing phase modulation light, and have transmission characteristics improved.SOLUTION: Light to be output from a light source 100 is subjected to a RZ modulation by a clock signal, a phase modulator 1041 for X polarization is subjected to a phase modulation by a first data signal, and a phase modulator 1042 for Y polarization is subjected to the phase modulation by a second data signal. In order for a phase deviation between the first data signal and the clock signal to be brought closer to 0 (zero), in a state where a data signal for the Y polarization is turned OFF, and the phase modulator 1042 is subjected to a bias control at an extinction point, an amount of phase shift of a phase shifter 1024 when an output of a polarization- multiplexing phase modulator 104 is maximum is specified. Further, in order for a phase deviation between the second data signal and t
