Provided are a method for forming at least a tooth root in a tooth containing a tooth crown through in vitro culturing i.e., without using xenotransplantation or allotransplantation techniques (in vivo culturing) and a regenerated tooth obtained by the method. This method is a method for forming at least a tooth root in a tooth containing a tooth crown, the method including forming a culture core containing the tooth and a cell-containing base material, the tooth being wrapped with the cell-containing base material, and culturing the culture core in a medium so as to form at least the tooth root in the tooth contained in the culture core, wherein the cell-containing base material contains at least one kind of cells selected from periodontal ligament-derived cells, bone marrow-derived cells, dental follicle-derived cells, dental pulp-derived cells and dental papilla-derived cells and wherein the medium contains predetermined components.
