PROBLEM TO BE SOLVED: To provide an isolated monoclonal antibody, particularly a human monoclonal antibody which specifically binds to fucosyl-GM1 with high affinity.SOLUTION: There is provided an isolated human monoclonal antibody, or an antigen-binding portion thereof which specifically binds to fucosyl-GM1, and which binds to a human small cell lung cancer cell line DMS-79. Disclosed are a nucleic acid molecule encoding the antibody, an expression vector comprising the nucleic acid molecule, a host cell comprising the expression vector, and a method for expressing the antibody which uses the host cell, and an immunoconjugate, a bispecific molecule, and a pharmacological composition comprising the antibodies.【課題】単離されたモノクローナル抗体、特にフコシルGM1に高い親和性で特異的に結合するヒトモノクローナル抗体を提供する。【解決手段】フコシルGM1に特異的に結合し且つヒト小細胞肺癌細胞株DMS-79に結合する、単離されたヒトモノクローナル抗体又はその抗原結合部分。前記抗体をコードする核酸分子、前記核酸分子を含む発現ベクター、前記発現ベクターを含む宿主細胞及び前記宿主細胞を用いる抗体を発現させるための方法、並びに前記抗体を含む免疫接合体、二重特異性分子及び薬学的組成物。【選択図】図16