Cellular senescence contributes to tissue and organismal aging, tumor suppression and progress, tissue repair and regeneration, and age-related diseases. Thus, aging intervention might be a promising target for treatment and prevention of diverse age-related diseases. In the present study, we investigated whether juglanin purified from the crude extract of Polygonum aviculare exerted inhibitory activity against cellular senescence in human dermal fibroblasts (HDFs). Juglanin decreased senescence-associated β-galactosidase activity (SA-β-gal) and the level of reactive oxygen species in senescent cells induced by adriamycin treatment. Juglanin also repressed SA-β-gal activity in HDFs under replicative senescence. These results suggest that juglanin represses cellular senescence in HDFs and might be useful for the development of dietary supplements or cosmetics that alleviate tissue aging or age-related diseases.