© 2017 The Japan Society of Applied Physics. Metalorganic chemical vapor deposition (MOCVD) is one of the suitable techniques for practical applications of BiFeO3films. To develop the potential of MOCVD as a device fabrication process, we investigated the relationship between the film and gas compositions, and the growth under highly oxidizing conditions using O2 and O3gases. In the growth of epitaxial BiFeO3thin films on SrRuO3-covered 4° vicinal SrTiO3(001) at 620 °C, the self-regulation of the film composition was achieved for Bi and Fe precursor supply ratios between 62.1 to 78.5% under O2and 56.1 to 73.2-under 5 wt-O3-mixed O2 atmospheres. The leakage was very sensitive to the precursor supply ratio and oxidizing gas. 150-nm-thick MOCVDBiFeO3films grown using O2+O3gas showed the minimum leakage current density of 2.3 × 10-7A/cm2at +1 V. The highly oxidizing growth conditions using O3can suppress the leakage while precise composition control is required.