A cDNA comprising a polynucleotide sequence that encodes a heavy chain and a light chain of an antibody or a functional fragment thereof that specifically recognizes one or more polypeptides, comprising an amino acid sequence described at any one of the following points (a ) a (i) and inhibits osteoclast formation and / or osteoclast 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； and (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 that includes the substitution, deletion or addition of only one amino acid residue in the amino acid sequence described in (a) to (h).Un ADNc que comprende una secuencia de polinucleótidos que codifica una cadena pesada y una cadena ligera de un anticuerpo o un fragmento funcional del mismo que reconoce específicamente uno o más polipéptidos, que comprende una secuencia de aminoácidos descrita en uno cualquiera de los siguientes puntos (a) a (i) e inhibe la formación de osteoclastos y/o la resorción ósea osteoclástica: (a) una secuencia de a
