an object of the present invention is to provide a method for preparing osteoblasts that are applicable , without causing risk of canceration , to bone defect repair or to the treatment of bone resorption , fracture , osteoporosis , or the like . to solve this problem , the present invention provides a method for preparing osteoblasts , the method comprising culturing mammal differentiated somatic cells in a medium in the presence of at least one compound selected from the group consisting of statin compounds , casein kinase 1 inhibitors , camp inducers , and histone methyltransferase inhibitors , to convert the somatic cells into osteoblasts .