<;P>;PROBLEM TO BE SOLVED: To provide a novel means that exhibits sufficient effects only on a cancer cell while hardly causing side effects on a normal cell. <;P>;SOLUTION: The kit for inducing a change of a sugar chain structure at the surface of a cancer cell comprises extracts of fucoidan. Preferably, the kit further comprises a sugar chain-recognizing protein or a cell expressing a sugar chain-recognizing protein. <;P>;COPYRIGHT: (C)2009,JPO&INPIT