The invention relates to a method for discriminating dioscorea nipponica makino from dioscorea doryophora. The method comprises the following steps of: (a) dying internal organizations of test materials which are suspected as dioscorea nipponica makino or dioscorea doryophora or measuring the content of dioscin; and (b) discriminating dioscorea doryophora and dioscorea nipponica makino through the dyed organizatios, wherein the material with the periderm dyed into a red color and composed of a phellem layer is dioscorea doryophora, the material with periderm dyed into a blue color and composed of a phellem layer, a phellem froming layer and a phellem skin layer is dioscorea nipponica makino, or dioscorea nipponica makino and dioscorea doryophora are discriminated from each other by the content (mg) of the dioscin serving which is meaaured with the dry weights (g) of the test matetials.