INDUSTRIAL APPLICABILITY According to the present invention, there are provided a therapeutic or prophylactic agent for diseases in which osteoclast activation is enhanced, such as rheumatoid arthritis containing an anti-VDAC antibody, and a human osteoclast formation inhibitor containing an anti-VDAC antibody.本発明により、抗VDAC抗体を含有する関節リウマチ等、破骨細胞の活性化が亢進している疾患の治療剤又は予防剤及び抗VDAC抗体を含有するヒト破骨細胞形成抑制剤を提供する。