This study was performed to evaluate the effect of Kangwhal-Sokdan tang(KS) on osteoblast function and gene expression. The osteoblast separated from the murine calvariae and MG-63 cell were cultivated to evaluate the cell function and gene expression. The results were summarized as followes. 1) KS increased cell proliferation of murine calvarial cell. 2) KS increased protein synthesis, collagen synthesis and ALP activity of murine calvarial cell. 3) KS increased the survival rate of murine calvarial cell. 4) KS increased the expression of calcitonin receptor and PTH receptor. 5) KS increased the expression of PKA and PKC. 6) KS decreased the expression of $PLA_2$, COX, $PGE_2$ synthase, but increased prostacyclin synthase. 7) KS increased the expression of collagen(type IV) gene. It is concluded that KS might improve the osteoporosis resulted from augumentation of osteoblast proliferation and gene expression.