Abstract: A volatilization suppressing agent comprising at least one thermosensitive polymer as an effective component is disclosed. Also disclosed is a volatile composition comprising a volatile effective component or an effective component carried by a volatile solvent and at least one thermosensitive polymer are disclosed. The use of the volatilization suppressing agent can suppress volatilization of volatile components when temperature rises and, as a result, volatilization of the volatile components is less affected by the temperature change. It is therefore possible to volatilize volatile components from air fresheners, deodorants, insecticides, moth proofers, repellents, attractants, antimicrobial agents, antifungal agents, antioxidants, and ozone decomposition agents more economically and to prevent troubles due to excessive volatilization.