We successfully fabricated perovskite oxide-based resistance random access memory (RRAM) with improved resistance switching characteristics, at a low temperature. A high-pressure oxygen-annealed (HPOA) W/Al/Pr0.7Ca0.3MnO3 (PCMO)/Pt device shows good memory characteristics such as device uniformity, endurance, and improved switching speed. X-ray photoelectron spectroscopy reveals large amounts of oxygen effectively incorporated into the PCMO layer during HPOA, enhancing the crystallization of PCMO at low temperature. X-ray diffraction analysis confirmed that an amorphous PCMO layer was converted to a polycrystalline structure. These results suggest that HPOA is a promising method for fabricating reliable perovskite oxide-based RRAM at a low temperature.