A method for monomerization of MMP-7 aggregates is provided. A method for monomerization of MMP-7 aggregates which comprises treating MMP-7 aggregates with a buffer solution comprising a monovalent cation chloride (sodium chloride, potassium chloride, etc.) at a low concentration or with a buffer solution not comprising a monovalent cation chloride, a process for preparing MMP-7 which involves said method for monomerization, and a (pharmaceutical) composition comprising MMP-7 in the aforementioned buffer solution. In case that a (pharmaceutical) composition comprising MMP-7 at a low concentration is prepared, the aforementioned buffer solution comprising sugar alcohols or sugars is used.
