Anti-human DLK-1 showing the antitumor activity in vivo

An antibody to Dlk-1 protein, which has antitumor activity in vivo, wherein: - the amino acid sequences of CDRs 1 to 3 of the V region of the H chain of the antibody are the amino acid sequences shown in SEQ ID NO : 30 to 32, respectively; and - the amino acid sequences of CDRs 1 to 3 of the V region of the antibody L chain are the amino acid sequences shown in SEQ ID NO: 33-35, respectively.