An anti-DR5 antibody, or a functional fragment thereof, having antigenic binding activity, characterized in that it contains: (a) a heavy chain variable region sequence selected from the group consisting of the following amino acid sequences: a1) a amino acid sequence comprising amino acid residues 20 to 141 of the amino acid sequence represented by SEQ ID NO: 34； a2) an amino acid sequence comprising amino acid residues 20 to 141 of the amino acid sequence represented by SEQ ID NO: 36； a3) an amino acid sequence comprising amino acid residues 20 to 141 of the amino acid sequence represented by SEQ ID NO: 38； a4) an amino acid sequence comprising amino acid residues 20 to 141 of the amino acid sequence represented by SEQ ID NO: 40； a5) an amino acid sequence comprising amino acid residues 20 to 141 of the amino acid sequence represented by SEQ ID NO: 44； a6) an amino acid sequence comprising amino acid residues 20 to 141 of the amino acid sequence represented by SEQ ID NO: 46； a7) an amino acid sequence comprising amino acid residues 20 to 141 of the amino acid sequence represented by SEQ ID NO: 48； a8) an amino acid sequence comprising amino acid residues 20 to 141 of the amino acid sequence represented by SEQ ID NO: 50； and (b) a light chain variable region sequence selected from the group consisting of the following amino acid sequences: b1) an amino acid sequence comprising amino acid residues 21 to 134 of the amino acid sequence represented by SEQ ID NO: 28； b2) an amino acid sequence comprising amino acid residues 21 to 134 of the amino acid sequence represented by SEQ ID NO: 30； b3) an amino acid sequence comprising amino acid residues 21 to 134 of the amino acid sequence represented by SEQ ID NO: 32； b4) an amino acid sequence comprising amino acid residues 21 to 134 of the amino acid sequence represented by SEQ ID NO: 52； b5) an amino acid sequence comprising amino acid residues 21 to 134 of the amino acid sequence represented by SEQ ID NO: 58； b6) an amino
