The present invention provides anti-N3pGlu A β antibody or its antigen-binding fragment. In addition, the present invention provides anti-N3pGlu A β antibody or its purposes of antigen-binding fragment in the treatment of Alzheimer disease.本發明提供抗N3pGlu Aβ抗體或其抗原-結合片段。另外,本發明提供抗N3pGlu Aβ抗體或其抗原-結合片段在阿爾茨海默病的治療中的用途。