A variety of Panax species grow and/or are cultivated widely in the Northern hemisphere from the Himalayas through China and Japan to North America. Panax species mainly consist of Panax ginseng, Panax quinquefolium, Panax notoginseng, and Panax japonicus. The most famous variety is P. ginseng, which was recorded in Chinese Materia Medica, 2000 years ago. In the components of Panax species, the major active component is ginsenoside, a dammarane-type saponin. In order to solve the simple and quick analysis of ginsenosides and to reach the one-step isolation of ginsenosides, anti-ginsenosides Rb1, Rg1, and R1 monoclonal antibodies (MAbs) have been prepared. As one of application of MAb against ginsenosides, we set up an unique new staining system named as eastern blotting that ginsenosides can be separated by thin layer chromatography and then blotted to a membrane, which was treated with NaIO4 and added carrier protein, then stained by the following steps, addition of MAb, secondary MAb conjugated with enzyme and finally substrate. Immunoassay-guided fractionation of the methanol extract of American ginseng and column chromatography led to the isolation of two new minor ginsenosides. Furthermore, the author succeeded to prepare the knockout extract of which an antigen, ginsenoside Rb1 can be removed from the crude ginseng extract by an affinity column combined with anti-ginsenoside Rb1 MAb. Clear immunohistochemistry of ginsenoside Rb1 in ginseng tissues was obtained by anti-ginsenoside Rb1. From these kinds of evidence, it became clear that MAbs against ginsenosides can be applied widely for the field of ginseng studies.