In order to quantitatively measure an Amadori compound by a simple optical method utilizing light scattering, a sample containing an Amadori compound which is stored in a cell is irradiated with excitation light from an He--Ne laser unit so that scattered light from the sample is received and separated into its spectral components for obtaining a light scattering spectrum, and a light scattering peak existing at 820 to 840 cm.sup.-1, 1655 to 1660 cm.sup.-1, 2000 to 2020 cm.sup.-1, 2080 to 2100 cm.sup.-1, 2460 to 2470 cm.sup.-1 or 2530 to 2600 cm.sup.-1 in shift wavenumber with respect to the excitation wavelength in the light scattering spectrum is detected by a detector. The saccharide concentration or the saccharification ratio of the Amadori compound is measured by a calibration curve through the peak intensity or the peak integral value of the light scattering peak.