[Problem] To provide: a cosmetic base material which can hydrophobize the surface of hair that is damaged and therefore loses hydrophobicity of the surface thereof and is deteriorated in functional properties and which can impart flexibility moisture retaining properties smoothness and gloss to hair and a cosmetic which contains the cosmetic base material. [Solution] A cosmetic base material characterized by comprising a peptide or a peptide derivative each containing an acidic amino acid as a constituent amino acid wherein at least a part of anionic functional groups forms an ion complex with at least one surfactant selected from the group consisting of cationic surfactants and amphoteric surfactants and a cosmetic containing the cosmetic base material.
