Disclosed is an antibody capable of binding to DLL3 protein. Preferably, the antibody can recognize an amino acid region lying between the 216th amino acid residue and the 492nd amino acid residue in human DLL3 that comprises the amino acid sequence represented by SEQ ID NO:1. Also disclosed are: a pharmaceutical composition, such as an anti-cancer agent, which contains the antibody as an active ingredient a method for diagnosing cancer using the antibody and a diagnostic agent for cancer, which comprises the antibody.
