The phytochemical study of the aerial parts of Aster scaber THUNB. (Asteraceae) yielded a new caffeoyl quinic acid, (-) 3, 5-dicaffeoyl-muco-quinic acid (2) and three known compounds, (-) 3, 5-dicaffeoyl quinic acid (1), (-) 4, 5-dicaffeoyl quinic acid (3), (-) 5-caffeoyl quinic acid (4). The structures were established by high resolution spectroscopic methods. The antiviral effects against HIV-1 integrase of the compounds was evaluated. (-) 3, 5-Dicaffeoyl-muco-quinic acid (2) exhibited potent antiviral activity with an IC₅₀ value of 7.0±1.3 μg/ml.