The present invention relates to a composition for dyeing keratin fibers, comprising (a) at least one direct dye； and (b) at least one sulfone compound represented by the following formula (I): wherein each of R1 and R2 independently denotes a monovalent C1-30 aliphatic group or a monovalent C6-30 aromatic group, which may optionally be substituted with at least one substituent； or R1 and R2, together with the sulfur atom which they are binding, form a 3-10 membered ring which may optionally be substituted with at least one substituent. The composition according to the present invention is a one-part composition and can prevent or reduce skin staining by the direct dye on the skin such as the scalp, while providing the keratin fibers with good cosmetic effects such as good coloring properties.
