As an anti-tumor drug having an excellent anti-tumor effect and excellent safety and also having an excellent therapeutic effect, an antibody-drug conjugate is provided, said conjugate being characterized by being produced by linking an anti-tumor compound represented by formula (1) to an anti-HER2 antibody through a linker having a structure represented by the formula: L1-L2-LP-NH-(CH2)n1-La-Lb-Lc- or the formula: -L1-L2-LP- (in the conjugate, the anti-HER2 antibody is bound at the terminal of L1, and the anti-tumor compound is bound at the terminal of Lc or LP wherein a nitrogen atom in an amino group located at position-1 in the anti-tumor compound serves as a binding site).本發明提供一種抗體-藥物結合物，其係作為抗腫瘤效果及安全性方面優異之具有優異治療效果的抗腫瘤藥，其特徵為使下式所示的抗腫瘤性化合物與抗HER2抗體，介隔下式：L1-L2-LP-NH-(CH2)n1-La-Lb-Lc-或-L1-L2-LP-所示的結構之連接物(linker)而結合(抗HER2抗體係於L1之末端結合，抗腫瘤性化合物係將1位之胺基之氮原子作為結合部位，而與Lc或LP之末端結合)。
