An object of the present invention is to obtain an anti-Repulsive Guidance Molecule a (RGMa) antibody having high binding activity and few side effects, which can be used as a medicament for the prevention, treatment or recurrence prevention of neurological diseases or immunological diseases. And an isolated RGMa-binding protein that does not inhibit the binding of RGMa and Neogenin and neutralizes the neurite growth inhibitory activity of RGMa, preferably the amino acid sequence of the complementarity determining region is SEQ ID NO: 30 in the Sequence Listing. The problem is solved by providing an anti-RGMa antibody that is -35 or SEQ ID NO: 36-40 of the sequence listing and SFG.本発明は、神経学的疾患または免疫学的疾患の予防、治療または再発予防用の医薬として使用し得る、結合活性が高く、副作用の少ない抗Repulsive Guidance Molecule a(RGMa)抗体を得ることを課題とし、RGMaとNeogeninの結合を阻害せず、かつRGMaの神経突起成長阻害活性を中和する、単離されたRGMa結合タンパク質、好ましくは、相補性決定領域のアミノ酸配列が配列表の配列番号３０～３５または配列表の配列番号３６～４０およびSFGである、抗RGMa抗体を提供することによりその課題を解決する。
