Provided is a surface-treated powder having excellent usability and adhesion to skin. The powder is coated with a surface-treating agent including (a) a fluorine-containing monomer of a general formula (I) and (b) an alkoxy group-containing monomer of a general formula (II). The powder is used for various cosmetics. [Chemical formula 3] CH2=C(-X)-C(=O)-Y-[-(CH2)m-Z-]p-(CH2)n-Rf (I) [Chemical formula 4) CH2=C(X1)-C(=O)-O-(RO)q-X2 (II)