In the present invention, CDR1, CDR2 and CDR3 of the antibody light chain variable region are the amino acid sequences shown by SEQ ID NO: 3, SEQ ID NO: 4 and SEQ ID NO: 5, respectively, and CDR1, CDR2 and CDR3 of the heavy chain variable region are respectively SEQ ID NO: 8, the monoclonal antibody or its derivative that antagonizes/inhibits the binding between the human PD-1 antigen and its ligand, which is the amino acid sequence represented by SEQ ID NO: 9 and SEQ ID NO: 10, is disclosed. In addition, the manufacturing process of the humanized antibody and the amino acid sequences of the heavy chain variable region and the light chain variable region of the humanized antibody are disclosed.本発明は、抗体軽鎖可変領域のＣＤＲ１、ＣＤＲ２およびＣＤＲ３はそれぞれ配列番号３、配列番号４および配列番号５で示されるアミノ酸配列であり、重鎖可変領域のＣＤＲ１、ＣＤＲ２およびＣＤＲ３はそれぞれ配列番号８、配列番号９および配列番号１０で示されるアミノ酸配列であるヒトＰＤ－１抗原とそのリガンドの結合を拮抗・阻害するモノクローナル抗体またはその誘導体を公開する。また、当該抗体のヒト化の製造過程および当該ヒト化抗体の重鎖可変領域と軽鎖可変領域のアミノ酸配列を公開する。
