PROBLEM TO BE SOLVED: To provide an antitumor drug having excellent antitumor effect and safety and having excellent therapeutic effect. An anti-tumor compound represented by the following structural formula and an anti-HER2 antibody are prepared by the formula: L1-L2-LP-NH-(CH2)n1-La-Lb-Lc- or -L1-L2-LP-. An antibody-drug conjugate characterized in that it is bound via a linker having a structure shown in (an anti-HER2 antibody binds at the end of L1, and an antitumor compound binds to the nitrogen atom of the amino group at position 1). As a site, it binds to the end of Lc or LP). [Selection diagram] None【課題】抗腫瘍効果と安全性面に優れる、優れた治療効果を有する抗腫瘍薬の提供。【解決手段】下記構造式で示される抗腫瘍性化合物と抗ＨＥＲ２抗体とを、式：L1-L2-LP-NH-(CH2)n1-La-Lb-Lc-又は-L1-L2-LP-で示される構造のリンカーを介して結合させたことを特徴とする抗体－薬物コンジュゲート（抗ＨＥＲ２抗体はL1の末端において結合し、抗腫瘍性化合物は、１位のアミノ基の窒素原子を結合部位として、Lc又はLPの末端に結合する）。【選択図】なし
