Disclosed are an aqueous cosmetic preparation including at least (A) astaxanthin, (B) 20 µg/L or more of iron ions, and (C) an iron chelating agent, and a method for suppressing the decomposition of astaxanthin in which (C) an iron chelating agent is included in an aqueous composition including at least (A) astaxanthin and (B) 20 µg/L or more of iron ions.