The present invention has an objective to provide a surface treatment agent which is safe with no generation of hydrogen, can be suitably used in a surface treatment of powder(s), exhibits good compatibility with other raw materials of cosmetics, and therefore, can improve a dispersing property and stability of powder(s) contained in a cosmetic, as well as provide a powder which has been subjected to a surface treatment with the aforementioned powder treatment agent, and a cosmetic raw material and a cosmetic which are produced by blending them, exhibit superior storage stability, have a superior outer appearance, and exhibit a superior sensation during use. A sugar alcohol-modified organopolysiloxane having a specified structure is used in the powder treatment.
