A method for forming at least a tooth root in a tooth containing a tooth crown, 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 to form at least the tooth root in the tooth contained therein, 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 the medium contains a component contained in a conditioned medium of a serum-free-cultured cell line of a human uterocervical squamous carcinoma cell line; an additive containing at least one selected from IL-1β, IL-6, IL-8, IL-9, EGF, IGF-I, GH, PDGF-AB, VEGF, LIF, HGF, FGF-2, FGF-1, BMP-2, BMP-4, M-CSF, dexamethasone, insulin, thyroxine, thyrocalcitonin, ascorbic acid and β-glycerophosphate; or both of them.