PROBLEM TO BE SOLVED: To provide modified multi-copper oxidase, and stain (a hair dye) for keratin fiber, excelling in dyeing property with less damage and eruption of hair and the scalp using the modified multi-copper oxidase.SOLUTION: Multi-copper oxidase raises an isoelectric point by adding basic amino acid or substituting a specific residue of an amino acid sequence for a basic amino acid, and stain (a hair dye) for keratin fiber uses the multi-copper oxidase.