To provide a method of detecting abnormal bone metabolism by using a gene strongly expressed in an osteoclast； a 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. [Means for Resolution] 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.
