The aim of this study was to investigate the effect of Quercus mongolica (QM) which induce anti-photoaging process of skin in vitro. Bioassay-guided isolation of 80 % Me2CO extract of the leaves of QM led to the isolation and identification of six known phenolic compounds: pedunculagin (1), (−)-epigallocatechin (2), (+)-catechin (3), quercetin 3-O-(6″-O-galloyl)-β-d-glucopyranoside (4), kaempferol-3-O-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (5) and kaempferol 3-O-(6″-galloyl)-β-d-glucopyranoside (6). The effects of compounds 1–6 on expression of matrix metalloproteinase-1 (MMP-1) and type-I procollagen were further evaluated. Among them, compound 1 showed potent inhibitory effect on MMP-1 and the increased type-I procollagen synthesis in ultraviolet B-induced human fibroblast. These results suggest that pedunculagin, an ellagitannin, is a potential candidate for the prevention and treatment of skin aging.