PROBLEM TO BE SOLVED: To effectively decontaminate places such as places having aqueous solutions or soil contaminated by radioactive cesium by phytoremediation.SOLUTION: In the case that corns such as black glutinous corns are grown in places contaminated by radioactive cesium, radioactive cesium accumulates in the organs (particularly, roots) of the corns. By the use of corns such as black glutinous corns in accordance with the present invention, places such as places having aqueous solutions or soil contaminated by radioactive cesium can effectively be decontaminated by phytoremediation.