An optical transmitter includes a light source that outputs light superposed with a pilot signal having a predetermined frequency; an optical modulating unit that modulates the light from the light source according to an input electric signal; a detecting unit that detects a high-output-side maximum value of signal light output from the optical modulating unit, a fluctuation width of the high-output-side maximum value, and a fluctuation width of a low-output-side minimum value; a bias-potential adjusting unit that adjusts a bias potential of an electric signal to be input to the optical modulating unit based on the detected maximum value; and an amplitude adjusting unit that adjusts an amplitude of the electric signal to be input to the optical modulating unit based on the fluctuation width of the high-output-side maximum value and the fluctuation width of the low-output-side minimum value.