Objective : We studied the effect of Bambusae concretio Silicea (BCS) on bone metabolism. Methods : At first, we treated PTH, 1,25(OH)₂D₃, mononuclear cell conditioned medium (MCM) and IL-1 to osteoblast cells derived from mouse calvarial bone explants in vitro, and then investigated the activities of collagenolysis and bone resorption factors. Results : BCS extracts have no cytotoxicities in concentrations of 1-150 ㎍/ml. BCS had protective activity against PTH (5 units/ml), MCM (5%, v/v), 1,25(OH)₂D₃ (20 ng/ml), IL-1α(2 ng/ml) and IL-1β, (1 ng/ml)-induced collagenolysis in the mouse calvarial cells. And, pretreatment of BCS for 1 hr significantly reduced the collagenolysis. Furthermore, it was much more expressed at 16 hrs after BCS (50 ㎍/ml)-pretreatment. And, BCS significantly protected against enhanced collagenolysis induced by IL-1α and IL-1β. Conclusion : BCS extracts inhibited the bone resorption in mouse calvarial bone cell;, thus BCS could be used clinically for bone diseases.