In the work the Raman spectroscopy method was used in the study of model iron gall ink and ink of the ancient Russian manuscript codex of the XV century from the collections of the Department of Manuscripts of the Russian National Library (OR RNB). It should be noted that the closest in terms of the set of vibrational bands and relative intensities to the ink spectra of the manuscript were replicated inks made on the basis of tannins of gall nuts. The results of the study allow us to make an assumption about the type of ink of the ancient Russian manuscript codex of the XV century. Keywords: iron-gallic ink, Raman spectroscopy, ancient Russian ink of the manuscript codex.