I have studied on the chemical changes of the components of tea leaves, especially catechins, flavonoid pigments and amino acids, in the manufacture of black tea by two dimensional paper partition chromatography. On the chromatograms of catechins in the fresh leaves (1st crop, 1953) of Assam Kyang form (Ak), Assam hybrid(AN1), and sinensis(Cn), there was not so much qualitical differences. Sinensis(Cn) had the most flavonoid contents and Assam Kyang form had the least, but no flavonoid coloured green-blue by spraying with Fe (NH4)2(SO4)2 was found only on the chromatogram of sinensis Cn.In each process of black tea manufacture, oxidation of catechins was progressed almost the same way among the three varieties, but flavonoids underwent little or no chemical change during the whole manufacturing process.The chromatogram of withering tea leaves showed an increase of spot No.4(gallic acid), appearance of spot No.5(gallcatechin a gallate) and separation of No.3 into 2 spots. As the result of tea fermentation, spot No.2 (L-epigal-locatechin), No.3 (DL-gallocatechin) and No.6 (L-epigallocatechin gallate) belonged to the grouping which underwent more oxidation than another grouping, i. e. No.8(L-epicatechin gallate), No.9 (L-catechin) and No.10 (L-epicatechin). Spot No.4 showed a successive increase and No.1 (m-digallic acid) increased a little throughout manufacture.On the other hand, 11 amino acids and amides and 2 unidentified spots was confirmed on the chromatogram of the fresh tea leaves, that is, aspartic acid, glutamic acid, serine, glycine, asparagine, threonine, a-alanine, arginine, valine, theanine, and leucine were identified by specimen test and their positions on the chromatogram. One of the 2 unknown spots is believed to be glutathione, and the other is seemed to be one spot of these, glutamine, histidine or lysine. Throughout the manufacture of black tea, including fresh leaves and manufactured tea, any marked chemical change in all amino acids was not found.