Possible antibodies that specifically bind to PD-1 and functional fragments thereof, said antibodies or functional fragments thereof are PD-1 chimeric antibodies and functional fragments thereof, and PD-1 humanized antibodies and functional fragments thereof including. [Selection] Figure 4PD-1に特異的に結合する可能な抗体及びその機能的断片、前記抗体或その機能的断片は、PD-1キメラ抗体及びその機能的断片、並びにPD-1ヒト化抗体及びその機能的断片を含む。【選択図】図4