A high-quality (100)-oriented epitaxial Fe3Si films were grown on (100) MgO substrates by RF-magnetron sputtering. The full width at half maximum of the Fe3Si 400 rocking curve was 0.18°, when the film was grown at 750°C. The epitaxial films of 100 nm thicknesses had a smooth continuous surface. The coercive field (Hc) was approximately 10 Oe, and the saturation magnetization (Ms) was 900 emu/cm3, which are almost the same as those of bulk Fe3Si. The anisotropy constant (K
1) of magnetization indicated that the epitaxial Fe3Si films grown at 750°C mainly consisted of long range ordering phase (DO3 phase) and that the epitaxial films post-annealed at 900°C was constituted with ordering phase.