Highly accurate measurement of chromatic dispersions of a device under test that is an optical component is enabled with a simple structure comprising: propagating pump light having a wavelength λpump and probe light having a wavelength λprobe through the device; calculating the generation efficiency of the idler light with respect to the wavelength λpump by measuring the power of idler light having a wavelength λidler output from the device according to four-wave mixing generated in the device; seeking the frequency difference or wavelength difference between the pump light and the probe light that makes an extremum of generation efficiency of the idler light; calculating phase mismatch among the pump light wavelength having such frequency difference or wavelength difference, the probe light wavelength, and the idler light wavelength; and on the basis of such calculation results, calculating the chromatic dispersion of the device at the wavelength λpump.