To provide a novel substance that is useful as a level dyeing agent in dyeing textile materials, nitrogen-containing fiber materials, particularly wool.

The objective sulfuric ester mixture is produced by allowing a mixture of sulfuric esters represented by general formula I (wherein R1-R3 are, for example, the groups such as the R1OH is stearyl alcohol; R2OH is a reaction product between animal fat amine and ethylene oxide; R3OH is poly-ethylene glycol where a+b+c=2), a specific sulfuric ester and sulfuryl chloride to react with an alcohol mixture of R1OH, R2OH and R3OH.