As an antitumor drug which is excellent in terms of antitumor effect and safety, there is provided an antibody-drug conjugate in which an antitumor compound represented by the following formula is conjugated to an antibody via a linker having a structure represented by the following formula: -L1-L2-LP-NH-(CH2)n1-La-Lb-Lc- wherein the antibody is connected to the terminal of L1, and the anti-tumor compound is connected to the terminal of Lc the nitrogen atom of the amino group at position 1 as a connecting position.