To provide a bleach-fixing agent superior in handling, conveyance, storage stability and delivering performance even in the case of being composed of only one part and concentrated.

This bleach-fixing treatment agent which is composed of only one part and concentrated comprises as a bleaching agent, either of an iron (III).ethylenediamine succinate complex salt or an iron (III).ethylenediamine diglutaminate complex salt or both as a main component, being more effective in the case that the both complex salts comprise their optical isomers (S, S) and filled in a container having an oxygen feed rate of ≤10 ml/hr per 1 l of packed materials.