As an antitumor drug which is excellent in terms ofantitumor effect and safety, there is provided anantibody-drug conjugate in which an antitumor compound represented bythe following formula is conjugated to an antibody via alinker having a structure represented by the followingformula: -L1-L2-L P-NH-(CH2)n1 -L a-L b-L c- wherein the antibody isconnected to the terminal of L1, and the antitumor compoundis connected to the terminal of L c- with the nitrogen atom ofthe amino group at position 1 as a connecting position.
