Kimonos and other decorational cloths dyed with vegetable extracts are still favored today in this country. Making use of modern chemical knowledge, the author has attempted to show a few characteristic features of the traditional vegetable dyeing. Many plants contain more than one pigment, each exhibiting different color according to its chemical structure. Nat urally, occurring tannins have a very important role both in the dyeing and in the dyed color. Tannins have shown the greying effect on the dyed color. Thus, the visible color is that of a complex nature. The reasonable color quality, based on the measurements of tristimulus values, has shown that the tannins always decrease the chroma of dyed color, while which do not contain tannin, like flower usually exhibit clear color of high chroma.