A rapid method for analyzing lignin in paper using IR reflectance spectra from its surface was developed. IR absorption and reflectance spectra of model paper samples prepared from cellulose fibers obtained from deciduous and coniferous woods with various lignin contents were analyzed. The intensity of the lignin absorption band at 1510 cm^–1 after Kubelka–Munk transformation of the paper reflectance spectra and chemical data on the fiber lignin content were well correlated. The analytical relationship between the lignin content in the paper fibers and the intensity of the lignin absorption band was used to estimate the lignin concentration in samples of Russian stamping paper from the 19th century using their IR reflectance spectra. The cellulose structure parameter estimated from the paper reflectance spectra showed that sheets containing lignin (5–16%) consisted entirely of wood fibers and were supplemented with kaolin.