An experiment was made by preparing milled wood lignin (Björkman lignin) from pine (Pinus densiflora Sieb. et Zucc.), beech (Fagus crenata Blume) and rice straw. The pyrolysis products of these lignin preparations were analyzed by pyrolysis gas chromatography. 0.5 to 3.0mg of the sample was inserted in the pyrolytic injector head and pyrolyzed at 500°(600°) in helium. The columns were operated at 124° or 160-180°. The following column packings were used: 30% silicone oil DC 550 on celite 545, 5% diethylene glycol succinate (DEGS) on Chromosorb W, and 5% Apiezon N on Chromosorb W. The pine milled wood lignin gave guaiacol, 4-hydroxy-3-methoxytoluene, 4-hydroxy-3-methoxyethylbenzene, 4-hydroxy-3-methoxystyrene, 4-hydroxy-3-methoxypropylbenzene, eugenol, cis-isoeugenol, trans-isoeugenol, vanillin, and acetovanillone. The beech milled wood lignin gave, in addition to those mentioned above, pyrogallol-1, 3-dimethylether, 4-hydroxy-3, 5-dimethoxytoluene, 4-hydroxy-3, 5-dimethoxyallylbenzene. At higher temperature, for example at 600°, on the pine lignin pyrogram, the peaks due to 4-hydroxy-3, 5-dimethoxytoluene and 4-hydroxy-3, 5-dimethoxyethylbenzene appeared, which suggest the presence of syringyl propane unit in the pine lignin structure. The rice straw milled wood lignin gave a remarkably large amount of 4-hydroxystyrene and 4-hydroxy-3-methoxystyrene in addition to the wood-lignin pyrolysis products. However, when pyrolyzed after alkaline hydrolysis, the yield of the characteristic products extremely decreased. This fact will support the view that these ingredients have been produced from decarboxylation of the p-coumaric acid and ferulic acid which are combined to the monocotyledonous lignin as ester.