[Problem] To provide, with respect to oxidant-containing compositions used as hair dyes or hair bleaching agents/tint controllers, an oxidant-containing composition that can improve the formulation stability, and a method for using the oxidant-containing composition. [Solution] The present invention provides an oxidant-containing composition used upon mixing with an alkali agent-containing agent as a hair dye or hair bleaching agent/tint controller, and contains (A) at least 4 mass% of a hydrocarbon that is liquid at 25°C, (B) a nonionic surfactant having an HLB of not more than 8, and (C) a higher alcohol. The component (B) may be at least one selected from monoglycerol fatty acid esters and polyglycerol fatty acid esters.
