The invention concerns a method for obtaining grape pomace and/or seed tannin, comprising steps which consist in: (a) from fresh black or white grapes pomace and/or seed, carrying out a solid-liquid extraction of raw tannin fraction in an aqueous solvent; (b) eliminating the first solvent from the resulting extract to obtain a concentrate of the raw tannin fraction; and (c) purifying the raw tannin fraction to obtain said tannin: The method is characterised in that in step (a) sulphite water (H2O+SO2) is used as solvent, and in step (c) the raw tannin fraction is purified by selectively adsorbing the tannin polyphenol compounds on resin and by subsequent filtering. The invention also concerns the resulting tannin and its uses in particular as endogenous tannin in wine.