Disclosed is a novel method for formation of a tooth by producing a chimera embryoid body using an undifferentiated cell and a dental mesenchymal cell derived from a mammal of the same species as that of the target mammal and then cultivating the chimera embryoid body on a three-dimensional matrix. A tooth is formed by co-cultivating an undifferentiated cell and a dental mesenchymal cell derived from a mammal of the same species as that of the target mammal in the presence of an induction factor to produce a chimera embryoid body, and then cultivating the chimera embryoid body on a three-dimensional matrix. The cultivation of the chimera embryoid body on the three-dimensional matrix is performed either by cultivating the chimera embryoid body in a serum culture medium without the induction factor for three days; or cultivating the chimera embryoid body in a culture medium supplemented with the induction factor for two days, and further cultivating the chimera embryoid body in a serum culture medium without the induction factor for three days. The undifferentiated cell is at least one cell selected from all stem cells including an ES cell. The mammal is one selected from all mammals. The induction factor is activin, bone morphogenic protein 4, insulin growth factor 1, fibroblast growth factor 2, or transforming growth factor .beta.1.