A copolymer in which from 45 to 60% by mass of all monomer units are unsaturated monomers having a specific carbosiloxane dendrimer structure is disclosed, along with a composition, a cosmetic raw material, and a cosmetic containing the copolymer. The copolymer has excellent physical properties, including compatibility with other cosmetic raw materials, e.g. hardly soluble ultraviolet absorbers, and is capable of improving the compounding stability of cosmetics. The copolymer imparts cosmetics with good water resistance, sebum resistance, luster, tactile sensation, and adhesiveness to the hair or skin.
