To provide caninized antibodies against canine PD-1 that have a high binding affinity for canine PD-1, and a method for treatment of canine cancer using the antibodies.SOLUTION: The present invention provides a variant of a canine fragment crystallizable region (cFc region) having a specific sequence and genetically modified, a caninized antibody that has having the variant of cFc region, and a pharmaceutical composition having the canine antibody and a pharmaceutically acceptable carrier or diluent.SELECTED DRAWING: Figure 1【課題】イヌＰＤ－１に高い結合親和性を有するイヌＰＤ－１に対するイヌ化抗体、および、前記抗体を用いるイヌの癌の処置方法の提供。【解決手段】特定の配列を有し、遺伝的に修飾されたイヌ結晶性フラグメント領域（ｃＦｃ領域）の変異体又は前記ｃＦｃ領域の変異体を含むイヌ化抗体、および、前記イヌ化抗体と医薬的に許容される担体または希釈剤とを含有する医薬組成物。【選択図】図１
