Abstract: Disclosed is a novel use of an immunoglobulin Fc fragment, and more particularly, a pharmaceutical composition comprising an immunoglobulin Fc fragment as a carrier. The pharmaceutical composition comprising an immunoglobulin Fc fragment as a carrier remarkably extends the serum half-life of a drug while maintaining the in vivo activity of the drug at relatively high levels. Also, when the drug is a polypeptide drug, the pharmaceutical composition has less risk of inducing immune responses compared to a fusion protein of the immunoglobulin Fc fragment and a target protein, and is thus useful for developing long-acting formulations of various polypeptide drugs.