A system and method include a wavelength shift correction light source emitting wavelength shift correction emission-line light and a spectrometer including: a spectroscopic unit receiving with photoelectric conversion elements rays of dispersed spectral light obtained by dispersing incident light based on wavelength, and outputs electrical signals corresponding to light intensities of the rays of dispersed spectral light; and a unit that measures temperature of the spectroscopic unit. When the wavelength shift correction emission-line light is measured as the incident light with the spectrometer, this system and method determine wavelength shift correction time emission-line wavelength corresponding to wavelength shift correction emission-line light, based on electrical signals from photoelectric conversion elements receiving wavelength shift correction emission-line light, and the measured temperature. The system and method determine wavelength variation from the difference between determined wavelength shift correction time emission-line wavelength and known emission-line wavelength of the wavelength shift correction emission-line light.