A peptide according to the present invention can perform a function identical or similar to the function of natural CTLA-4 and has an excellent degree of skin penetration due to a small size. The peptide according to the present invention effectively binds to antigen presenting cell surface proteins (CD80 and CD86) to inhibit activity of T cells and thus is capable of inhibiting the expression of inflammatory cytokines (for example, IL-2 and IFN-γ). As a result, a composition comprising the peptide according to the present invention exhibits excellent effects in terms of preventing, treating, or improving Th1-mediated immune diseases. Therefore, the superior activity and stability of the peptide according to the present invention can be useful when applied to medicine, quasi-drugs, and cosmetics.