It is an object of the present invention to provide an antibody binding to CDH6 and having internalization activity, an antibody-drug conjugate of the antibody and a drug having antitumor activity, a pharmaceutical product comprising the antibody-drug conjugate and having therapeutic effects on a tumor, a method for treating a tumor using the antibody, the antibody-drug conjugate or the pharmaceutical product, and the like. The present invention provides an anti-CDH6 antibody having internalization activity, an antibody-drug conjugate of the antibody and a drug having antitumor activity, a pharmaceutical product comprising the antibody or the antibody-drug conjugate, and a method for treating a tumor.
