The present invention includes an antibody that binds to HS6ST2 protein, a pharmaceutical composition containing the antibody as an active ingredient, a method for diagnosing cancer using the antibody, a HS6ST2 protein to which a cytotoxic substance is bound, and the HS6ST2 protein as active ingredients A pharmaceutical composition is provided.本発明は、HS6ST2タンパク質に結合する抗体、該抗体を有効成分として含む医薬組成物、該抗体を用いた癌の診断方法、細胞傷害性物質が結合したHS6ST2タンパク質および該HS6ST2タンパク質を有効成分として含む医薬組成物を提供する。