Background : Campanula takesimana is a herb(Jabanpungnyeoncho) used traditionally in the korea private and we tried the development on a medicinal material. It was known that it has chlorogenic acid, as a immunoadjuvant activity. In this study we investigated the contents of the chlorogenic acid in Companula takesimana at different harversting time by the high performance liquid chromatographic(HPLC)-PDA. Campanula takesimana was collected on May maddle (Flower buds farmed), June middle (flowers opened) and July middle (seeds were mature). Methods and Results : HPLC analysis was carried out using X-bridge C18 column (5um, 250*4.6mm) and a mobile phase consisting of acetonitrile and water containing 0.1% formic acid at a flow rate of 1.0 ml/min. The optimum wavelength for the detection of the Chlorogenic acid was 330 nm using Photo Diode Array Detector. The contents of the chlorogenic acid in the Campanula takesimana extrat were 1.00% (May middle), 0.84% (June middle), 0.05% (July middle), respectively. As the different parts of Campanula takesimana, chlorogenic acid contents in May middle extrat were 2.73% (aerial part), 0.05% (root) and in June middle extrat were 1.61% (aerial part), 0.03% (root), 0.70% (flower) and in July middle were 0.13% (aerial part), 0.03% (root), 0.00% (seed), respectively. Conclusion : From the above results, the highes content of chlorogenic acid was observed in aerial part and May middle extract of Campanula takesimana.