Pseudocubic SrRuO3 (100) epitaxial thin films were fabricated on Si (100) with a YBa2Cu3Ox / CeO2 / YSZ (yttria-stabilized-zirconia) triple buffer layer ∼ 14 nm thick by pulsed laser deposition (PLD). Reflection high-energy electron diffraction (RHEED) and X-ray diffraction (XRD) revealed that the first buffer layer of YSZ (100) was epitaxially grown on naturally oxidized Si (100) substrates with the process condition of P
B (base pressure) = 1×10-Torr, P
O2 (oxygen partial pressure) = 5×10- Torr, and T
s (substrate temperature) = 700 °C. Higher deposition rate of YSZ in the range of 0 ∼ 0.6 nm/min brought about better crystallinity with a smaller value of a full-width at half maximum (FWHM) in the YSZ (200) rocking curve. Subsequent deposition of CeO2, YBa2Cu3Ox, and SrRuO3 resulted in an SrRuO3 (100) epitaxial thin film exhibiting good crystallinity with FWHM = 1.7° in the SrRuO3 (200) rocking curve.