Plants are an invaluable source of potential new anti-cancer drugs. Sasa quelpaertensis Nakai (Korean name, Jeju-Joritdae) is one of these plants with medical value, which is a bamboo grass widely distributed in Mt. Halla on Jeju Island, Korea. Here, we investigated the apoptotic effects of S. quelpaertensis leaf extracts in six human cancer cell lines (A549, MCF-7, HepG-2, Hela, HCT116 and A375). MTT assay signified the antiproliferative nature of S. quelpaertensis extracts against all tested cancer cells: S. quelpaertensis displayed slight cytotoxicity against A549, MCF-7 and HepG-2 cells, whereas it was exclusively cytotoxic to Hela, HCT116 and A375 cells. Apoptotic cells were evaluated using PI staining of DNA fragmentation by flow cytometry (sub-G1 peak). PI staining indicated increasing accumulation of Hela, HCT116 and A375 cells at sub-G1 phase. Further events like generation of nitric oxide ($NO^{ullet}$) were accompanied in the S. quelpaertensis Nakai-induced apoptosis. Augmented $NO^{ullet}$ generation resulted in the DNA fragmentation of Hela, HCT116 and A375 cells by treatment with S. quelpaertensis leaf extracts. These results suggest that S. quelpaertensis may be a potential natural resource for treating cancer cell. To identify the exact mechanisms of molecular mechanism of S. quelpaertensis induced apoptosis awaits further investigation.