Lignins of Jatropha curcas organs were qualitatively and quantitatively characterized by thioglycolic acid, thioacidolysis, and nitrobenzene oxidation methods. The lignin content of the seed coat was 49.4%, and was the highest among various organs of the plant, while the stem had 15.9% lignin, within the range of usual lignin contents of angiosperm trees. Lignin aromatic components of all organs were composed of guaiacyl and syringyl units. Nitrobenzene oxidation indicated that the ratios of syringyl to guaiacyl lignins in the fruit coat and stem were higher than those in other organs. This study provides basic data for the total utilization of J. curcas wood.