PROBLEM TO BE SOLVED: To provide a technique for purifying a medium such as soil or water polluted with heavy metals by cultivating a fast-growing plant excellent in heavy metal absorbing capacity. SOLUTION: Crassocephalumcrepidioides is cultivated in a medium such as soil or water polluted with heavy metals to absorb heavy metals to purify the medium polluted with heavy metals. COPYRIGHT: (C)2009,JPO&INPIT