The present invention pertains t o an aqueous composition which contains 2 -amino - -(4 - Dromobenzoyl)phenvlacetic acid or a salt thereof and which may contain, if necessary, a benzalkonium chloride and/or a polyoxyethylene sorbitan fatty acid ester. The stability of 2-amino-3-(4-bromobenzoyl)phenylacetic acid or a salt thereof can be kept by restricting the contents of a benza -Ikonium chloride and a polyoxyethylene sorbitan fatty acid ester respectively within specific ranges, whereby a composition which does not suffer any appearance change can b e obtained.