Ru and RuO2 thin films were prepared by RF magnetron sputtering. The crystalline structure and electrical properties of these films were investigated. Reactive sputtering of a ruthenium metal target was carried out in a mixed gas of argon and oxygen at 580° C. Total pressure (P O2+P Ar) was controlled to maintain a constant pressure of 1 Pa. The RuO2 single phase could be obtained when P O2 was 0.5 Pa and the deposition rate was about 30 nm/min. The resistivity of the 290 nm-thick RuO2 thin films deposited on SiO2(1000 nm)/Si was 54.9 µ Ω· cm. However, the resistivity increased with decreasing film thickness. Fatigue resistance of (Pb, La)TiO3 thin films with RuO2 as top and bottom electrodes was improved compared to the films on Pt electrodes.