The present invention relates to a protein conjugate in which a physiologically active polypeptide and a biocompatible material are linked through a fatty acid derivative, thus having an extended duration of physiological activity compared to that of a natural type, and a method of preparing the same. The protein conjugate of the present invention in which a biocompatible material, fatty acid, and a physiologically active polypeptide are linked was confirmed to have an increased half-life of the physiologically active polypeptide, and thus can be widely used in the field of protein drugs.
