Epitaxial growth conditions of perovskite type oxide films on Si substrates are theoretically considered from a viewpoint of lattice matching. Then, epitaxial growth of SrTiO3 films and BaTiO3 films on Si (100) substrates has been tried, in which in order to deoxidize the SiO2 layers on the substrates, thin Sr layers are deposited prior to deposition of the oxide films. It has been found from X-ray diffraction, reflection high energy diffraction, and Rutherford backscattering analyses that SrTiO3 films grow epitaxially on Si (100) substrates under the optimum conditions of the Sr layer thickness, deposition temperature, and annealing temperature.