Abstract: Provided is a composition in which the dispersibility of a specific modified peptide is less likely to decrease at a pH of less than 7.0. The cosmetic composition contains a modified peptide having one or more side chain groups including one or more units selected from the group consisting of a structure represented by formula (Ia): —S—S—(CH2)n—COOH, wherein n is 1 or 2, a structure represented by formula (Ib): —S—S—CH(CH3)—COOH, a structure represented by formula (Ic): —S—S—CH(COOH)—CH2—COOH, and salts of these structures; and a long-chain alkyltrimethylammonium salt or an N-long-chain alkylpyridinium salt, wherein the ratio of the total content of the long-chain alkyltrimethylammonium salt and the N-long-chain alkylpyridinium salt to the content of the modified peptide is 0.5 or more, and the cosmetic composition has a pH of less than 7.0.