Provided are a composition for stimulating differentiation of MSCs into osteoblasts, which includes cryptotanshinone, and an osteogenesis stimulator including cryptotanshinone and MSCs. When the cryptotanshinone is treated to the MSCs, the differentiation into osteoblasts is stimulated, and thus osteogenesis of a patient may be stimulated by directly transplanting the differentiation-induced MSCs to the patient. Accordingly, the composition or osteogenesis stimulator may be used to treat patients having disability requiring stimulation of osteogenesis such as osteoporosis, bone fracture, bone grafting including alveolar bone grafting for implant placement, or other bone defects.