Identification of the age of ginseng root is very important in commercial market as well as in research field. However, any criterion abut it has not been clearly established yet. We studied to find a clear morphological key for identification of ginseng root\`s age using the histochemical staining method. Fresh sections of 3, 4, 5, and 6 year old roots were stained with 1% nile blue, observed under the light microscopy, and compared each other. The number of secretory duct layers(SDL) is a useful key to confirm the age of ginseng root as follow; three-year-old root has two, four-year-old one has three, fie-year-old one has four, and six-year-old one has five resin duct layers on each cortical region of roots. Secretory ducts are thought to be formed by the vascular cambium every year. Unlike the surrounding parenchyma cells, secretory epithelial cells lack starch grains in the cytoplasm.