The present specification relates to a composition containing novel (20S,24R)-6-O-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside-dammar-3-one-20,24-epoxy-6a,12b,25-triol, a pharmaceutically acceptable salt thereof, a hydrate or a solvate thereof as an active ingredient. The composition exhibits an excellent skin brightening effect.