FIELD : medicine.SUBSTANCE : group of inventions relates to medicine and cosmetic industry, specifically to a medicinal agent for preventing or treating hair loss, wherein said medicinal agent comprises a chemokine ligand protein 1 containing a CXC motif, (CXCL1) as an active ingredient, wherein said CXCL1 protein comprises an amino acid sequence presented in SEQ ID No : 1 relates to use of CXCL1 protein as a quasi-drug and as a cosmetic product for preventing or reducing hair loss, also relates to a medicinal agent for stimulating hair formation or hair growth, relates to use of CXCL1 protein as a quasi-medicinal agent and as a cosmetic agent for stimulating hair formation or hair growth, and also relates to a method for stimulating hair formation or hair growth.EFFECT : group of inventions provides preparing a drug which has no side effect in the treatment of hair loss and has an excellent hair formation effect even in a short period of time.11 cl, 3 dwg, 6 ex