The present invention relates to a composition for preventing hair loss and, more specifically, to a compound having a structure in which finasteride and a peptide are linked through a covalent bond and a pharmaceutical composition or a cosmetic composition for preventing hair loss or promoting hair growth comprising the same. The compound of the present invention having a structure in which finasteride and a peptide are linked through a covalent bond is excellent in physiological activities such as hair loss improvement, hair growth promotion, cell growth promotion, etc., is excellent in stability in water and skin permeation, and thus can be effectively used as a composition for preventing hair loss and promoting hair growth.