To provide an ambient temperature-curable polymer composition having good hardenability and adhesion, containing a low out-gas content, and being suitable as sealing materials for clean rooms, for example.

The ambient temperature-curable polymer composition includes (A) a polyoxyalkylene polymer wherein the main chain substantially includes polyoxypropylene and has a reactive silicon-containing group at an end of the main chain, (B) a curing catalyst, (C) an inorganic filler substantially containing no alkalimetal salt of fatty acid, (D) alkoxy silane and/or a hydrolyzed, condensed product thereof, and (E) hindered amine or hindered phenol antioxidant having a melting point of 20C or higher and 120C or lower or vaporization pressure at 20C of 1.110-3Pa or less, wherein the BHT content is 2 ppm or less to the total.