The present invention relates to: a method of preparing an osteoblast from a somatic cell of a mammal, the method including introducing a bone-related gene or an expression product thereof and a reprogramming-related gene or an expression product thereof, or introducing a reprogramming-related gene or an expression product thereof independently into the somatic cell, the bone-related gene including at least one kind selected from the group consisting of Runx2 (R), Osterix (O) , and Dlx5 (D), the reprogramming-related gene including at least one kind selected from the group consisting of Oct family, c-Myc (M), L-Myc (L), Klf family, Lin-28, and Sox2； and an osteoblast prepared by the method.
