This study was carried out to investigate change of ginsenoside contents according to tissue ratio in ginseng root by age and diameter. The epidermis-cortex and xylem-pith extent, fresh weight, dry weight of ginseng increased with the root age increase. They increased higher in xylem-pith than in epidermis-cortex. The ratio of epidermis-cortex decreased and xylem-pith increased as the main root diameter increased. In case of same diameter, the xylem-pith ratio increased by the increase of root age. The epidermis-cortex ratio was 4 > 5 > 6 years, respectively. The total 10 ginsenosides of epidermis- cortex increased with the root age increase. However, the total ginsenoside of xylem-pith decreased and it was 2~5 times lower than epidermis-cortex. The most of ginsenoside contents existed in epidermis-cortex. The diameter decrease in main root is related to the increase of epidermis-cortex ratio. It leads to increase of ginsenoside contents. In order to select high level of ginsenoside cultivar, it suggested that it should be selected main root having narrow diameter and lower epidermis- cortex ratio.