The chromatic dispersion of an optical component is measured with high accuracy using a simple set-up, which includes a pump light source, a probe light source, and a measuring means. Pump light having a wavelength λpump and probe light having a wavelength λprobe is propagated through an optical component, with the wavelength λprobe being apart from the wavelength λpump by a given frequency. The generation efficiency of the idler light with respect to the wavelength λpump is calculated by measuring the power of idler light having a wavelength λidler output from the optical component, and by seeking the pump light wavelength for making the generation efficiency a local extreme value, the chromatic dispersion of the optical component is calculated from the result of calculation of phase mismatch among the pump light wavelength having such wavelength as sought, the corresponding probe light wavelength, and the corresponding the idler light wavelength.