Disclosed are small interfering RNA (siRNA) that complementarily binds to a base sequence of Hif1a mRNA transcript thereby inhibiting expression of Hif1a without inducing immune responses and a use of the siRNA for prevention and/or treatment of cancer. Since Hif1a is commonly overexpressed in almost all cancer cells the siRNA that complementarily binds to Hif1a encoding mRNA may inhibit expression of Hif1a through RNA mediated interference (RNAi) thereby inhibiting proliferation and metastasis of cancer cells and thus the siRNA may be useful as an anticancer agent.
