TO PROVIDE A METHOD OF DETECTING ABNORMAL BONE METABOLISM BY USING A GENE STRONGLY EXPRESSED IN AN OSTEOCLASTA METHOD OF SCREENING A COMPOUND HAVING A THERAPEUTIC AND/OR PREVENTIVE EFFECT ON ABNORMAL BONE METABOLISM AND A PHARMACEUTICAL COMPOSITION FOR TREATING AND/OR PREVENTING ABNORMAL BONE METABOLISM. PROVISION OF A METHOD OF DETECTING ABNORMAL BONE METABOLISM BY USING THE EXPRESSION OF HUMAN SIGLEC-15 GENE AS AN INDEX A PHARMACEUTICAL COMPOSITION CONTAINING AN ANTIBODY WHICH SPECIFICALLY RECOGNIZES HUMAN SIGLEC-15 AND HAS AN ACTIVITY OF INHIBITING OSTEOCLAST FORMATION AND THE LIKE. FIG.1