Ultrastructural and anatomical features of the leaf were studied in Panax ginseng C.A. Meyer(ginseng). The ginseng leaf poorly developed palisade tissue and the size of mesophyll cell was larger and the chloroplast density was lower than that of Glycine max (soyben). Ginseng chloroplast was filled with highly stacked grana and condensely-arrayed thylakoid, so the stroma space was hardly absorbed. However, ginseng mesophyll tissue and chloroplast array did not reduce light energy entering the mesophyll chloroplast, and the high LHCP/CP ratio of ginseng thylakoid resulted in the absorption of excess photon. It is reasonable to assume that 1O1-photogenearation by excess light energy partially resulted from the anatomical and ultrastructural characteristics of the ginseng leaf.