A powdery composition comprising the following components (A), (B) and (C).A hair dyeing or bleaching kit composed of a first composition consisting of a powdery composition and a second composition comprising hydrogen peroxide.Component (A): an alkanolamine having an SP value by the Fedors method of 10 (cal/cm3)1/2 or more and 16 (cal/cm3)1/2 or less or a salt thereof；Component (B): a compound having an SP value by the Fedors method within ±6 (cal/cm3)1/2 inclusive of the SP value of the component (A) as an alkanolamine (with a proviso that compounds corresponding to component (A) are excluded from component (B))；Component (C): a powdery carrier.
