12P21a22122As an anti tumor drug having an excellent anti tumor effect and safety and also having an excellent therapeutic effect an antibody drug conjugate is provided which is characterized in that an anti tumor compound represented by formula (1) is linked to an anti HER2 antibody through a linker having a structure represented by the formula: L L L NH (CH)n L (CH)n C(=O) (wherein the anti HER2 antibody is linked at the terminal of L and the anti tumor compound is linked to a carbonyl group in a (CH)n C(=O) moiety wherein a nitrogen atom in an amino group located at position 1 in the anti tumor compound serves as a linking part).
