To provide powder regulating pH of the skin surface to weakly acidic, and gentle to the skin.

There is provided the surface-treated powder regulating the pH of the skin to 3.0-5.0. The power is obtained by treating the surface thereof with a resin having carboxylic acid functional group. Furthermore, the resin having carboxylic acid functional group is preferably polyacrylic acid, polymethacrylic acid, polymaleic acid, or a copolymer of acrylic acid and maleic acid, a copolymer of methacrylic acid and maleic acid, a copolymer of acrylic acid and methacrylic acid, and a copolymer of acrylic acid, methacrylic acid and maleic acid. A cosmetic containing the power is provided, and the cosmetic is particularly preferable as a makeup cosmetic.