It is intended to provide a purification medium whereby heavy metals can be effectively removed by growing a plant even in a humid environment such as a wetland, a river, a paddy field, a lake or a pond or an environment compositely contaminated with multiple heavy metals. Namely, a method of purifying a medium contaminated with heavy metals which comprises growing a plant belonging to Cyperaceae Eleocharisin the medium contaminated with heavy metals and then harvesting the plant after raising for a definite period of time. An Eleocharis plant can be easily grown even in en environment contaminated with heavy metals such as copper, arsenic, zinc and lead and absorbs and accumulates these heavy metals. Thus, it makes possible to efficiently remove heavy metals even in a humid environment.
