Long term and repeated exposure of ultraviolet light on the skin often induces chronic skin diseases such as skin cancer as well as photoaging, and the mechanisms of these skin damages are closely associated with up-regulation of matrix metalloproteinase's (MMPs) activities. The methylene chloride soluble fraction of methanol extract from the stems of Styrax japonica . (Styracaceae) showed significant MMP-1 inhibition in primary human skin fibroblasts cause by ultraviolet irradiation. Four triterpenoids were isolated by column chromatography. Among them, Erythrodiol-3-acetate reduced of MMP-1 and induced of type 1 procollagen at the protein levels in a dose-dependent manner.