Disclosed is an antibody, or a functional fragment of the antibody, which specifically recognizes one or more polypeptides comprising an amino acid sequence described in any one of the following (a) to (i) and inhibits osteoclast formation and/or osteoclastic bone resorption: (a) an amino acid sequence represented by SEQ ID NO: 2 in the Sequence Listing； (b) an amino acid sequence consisting of amino acid residues 21 to 328 of the amino acid sequence represented by SEQ ID NO: 2 in the Sequence Listing； (c) an amino acid sequence consisting of amino acid residues 1 to 260 of the amino acid sequence represented by SEQ ID NO: 2 in the Sequence Listing； (d) an amino acid sequence consisting of amino acid residues 21 to 260 of the amino acid sequence represented by SEQ ID NO: 2 in the Sequence Listing； (e) an amino acid sequence represented by SEQ ID NO: 4 in the Sequence Listing； (f) an amino acid sequence consisting of amino acid residues 21 to 341 of the amino acid sequence represented by SEQ ID NO: 4 in the Sequence Listing； (g) an amino acid sequence consisting of amino acid residues 1 to 258 of the amino acid sequence represented by SEQ ID NO: 4 in the Sequence Listing； (h) an amino acid sequence consisting of amino acid residues 21 to 258 of the amino acid sequence represented by SEQ ID NO: 4 in the Sequence Listing； and (i) an amino acid sequence including substitution, deletion or addition of one or several amino acid residues in the amino acid sequence described in (a) to (h). Also disclosed is the use of at least one of the antibodies or functional fragments of the antibodies for the manufacture of a medicament for treating and/or preventing abnormal bone metabolism.
