The Radix of Peucedanum japonicum (Umbelliferae) has been used for dispelling wind-damp, headache, chills and wind cold. In order to evaluate to quality of it, the method for the quantitative determination of peujaponiside $(peucedanol;7-O-{eta}-D-apiofuranosyl(1{ ightarrow}6)-{eta}-D-glucopyranoside)$ as standard compound has been developed. Peujaponiside is a major compound of Peucedani Radix. It was analyzed by HPLC using the solvent system of 15% $CH_3CN$. The amount of peujaponiside from Peucedani Radix are in the range 0.14% (n=20).