In order to form a homoepitaxial thin film on the surface of a substrate having LiNbO.sub.3 single crystal or LiTaO.sub.3 single crystal surface, a composition identical to that of the single crystal is formed by a high-frequency sputtering method on the surface of the substrate having LiNbO.sub.3 single crystal or LiTaO.sub.3 single crystal surface. Manufacturing apparatus for a homoepitaxial thin film includes a chamber and a high-frequency power source that supplies high-frequency power to a target disposed inside the chamber. Sputtering electrode is arranged such that a surface normal of the target is offset with respect to the substrate located at a film formation position, and is also arranged such that the surface normal of the target is inclined at an angle of 15 to 75 with respect to a surface normal of the substrate.