A method of quantitative analysis of a specific component of an object to be measured comprises steps of measuring an energy spectrum of light transmitted through or reflected from the object, dividing the energy spectrum into a plurality of wavelength domains, thereby obtaining a plurality of partial energy spectra, normalizing the plurality of partial energy spectra within each wavelength domain using an energy measured at a predetermined wavelength contained in each wavelength domain, and performing the quantative analysis by multivariate analysis using the plurality of partial energy spectra having been normalized.