PROBLEM TO BE SOLVED: To provide an anti-EphA4 antibody or an EphA4 binding fragment thereof capable of binding to EphA4 and inhibiting the binding between EphA4 and its ligand, and a pharmaceutical composition containing these as an active ingredient. A mouse anti-EphA4 antibody having binding affinity for EphA4 was obtained, and the complementarity determining region (CDR) sequence of the mouse anti-EphA4 antibody was identified. As a result, it was possible to produce a humanized antibody containing the CDR sequence of the mouse anti-EphA4 antibody in the variable region of the heavy chain and light chain. [Selection figure] None【課題】 ＥｐｈＡ４に結合し、ＥｐｈＡ４とそのリガンドとの結合を阻害し得る、抗ＥｐｈＡ４抗体またはそのＥｐｈＡ４結合断片、および、これらを有効成分として含む医薬組成物を提供する。【解決手段】 ＥｐｈＡ４に対して結合親和性を有する、マウス抗ＥｐｈＡ４抗体を取得し、当該マウス抗ＥｐｈＡ４抗体の相補性決定領域（ＣＤＲ）の配列を特定した。これにより、重鎖および軽鎖の可変領域に前記マウス抗ＥｐｈＡ４抗体のＣＤＲ配列を含むヒト化抗体の作製を可能となった。【選択図】なし
