A removing agent for heavy metal ion in water which comprises synthetic zeolite, wherein 10 mol % or more of a total amount of exchangeable cation is substituted with magnesium ion and 60 mol % or more thereof is substituted with magnesium ion and calcium ion, and activated carbon at a weight ratio of 2:98 to 50:50 can effectively adsorb and remove heavy metal ions such as lead in water as well as residual chlorine and trihalomethane efficiently, particularly, in tap water, so as to allow delicious and healthful water without disturbing the balance between calcium ion and magnesium ion.