The present invention relates to a novel use of the HIV NC protein, and more particularly, it is relates to a pharmaceutical composition for preventing and treating AIDS having a polypeptide comprising HIV NC protein as an active component and the method of inhibiting HIV proliferation by using the polypeptide. The polypeptide comprising HIV NC protein of the present invention, when it is overexpressed, has the effect on inhibiting HIV proliferation. Accordingly, the present invention provides not only the novel means of inhibition of HIV proliferation, but also the novel method for preventing and treating AIDS.