A new ursane-based compound, astilbotriterpenic acid (1), was isolated from the rhizomes of Astilbe chinensis. Its structure was determined on the basis of chemical evidence and extensive spectroscopic methods, including 1D- and 2D-NMR. The pentacyclic triterpenoid 1 was assayed for its in vitro cytotoxicity against Bcap37, HeLa, HepG2, HO-8910, K562, PAA, SGC7901, and P388 cancer cells, as well as for its apoptosis-inducing activity in HeLa cells. Compound 1 was found to strongly inhibit tumor-cell growth through induction of apoptosis and may, thus, be further evaluated as a novel chemotherapeutic agent.