Objectives : Effects of Rhodiola rosea root on cancers on stomach, breast, lung, and liver were examined. Methods : Water extracts and methanol extracts of Rhodiola rosea root were treated on cancer cells, and its effects on cancers were examined. Results : 1. Water extracts and methanol extracts of Rhodiola rosea root was less harmful in its lowest density 0.25 mg/mL (9.l%와 10.5%), but became more harmful as its density increased. 2. As for human stomach adenocarcinoma cells AGS, breast adenocarcinoma cells MCF-7, and lung carcinoma cells A549, methanol extracts showed 70-77% inhibition of cancer cells in high density(1 mg/mL), and water extracts showed 60-70% inhibition rate and its selective death rate was less than 2.5. Conclusion : Rhodiola rosea root can be used to treat cancers and to increase immunity.