An optical modulator includes a first optical modulation section and a second optical modulation section which use modulation signals different from each other when applying a modulation signal to the modulation electrode and performing optical modulation. In addition, a light-receiving element is disposed on a substrate, and the light-receiving element has a first light-receiving section that detects optical signal propagating from a first waveguide which guides the optical signal output from the first optical modulation section. In addition, the light-receiving element also has a second light-receiving section that detects an optical signal propagating through a second waveguide which guides the optical signal output from the second optical modulation section.