BiFeO3 is one of the most important candidates for realization of functional devices due to its good ferroelecricity, piezoelectricity and multiferroelectricity. BiFeO3 thin films have generally been prepared using sputtering, PLD (Pulsed Laser Deposition) and CSD (Chemical Solution Deposition) techniques. However, in these films, it was quite difficult to control stoichiometric composition and oxygen deficiencies in films which cause the high leakage. In order to obtain BiFeO3 thin films with low leakage current densities for an application to 3D-FeRAMs with nanowire capacitors, in our study, MOCVD (Metalorganic Chemical Vapor Deposition) process was used. In our MOCVD, Bi(C6H5)3 and Fe(thd)3 were used as an source precursor and O2 containg O3 as an oxidizing gas. BiFeO3(001) epitaxial thin films were successfully grown on SrRuO3/SrTiO3(100) at 620 oC. Process window in Bi/(Bi+Fe) was observed by changing Bi supply ratio. BiFeO3 thin films obtained showed good ferroelectric P-E hysteresis loops (Pr ~ 60μ C/cm2, Ec ~ 300 kV/cm). BiFeO3 thin films gown by MOCVD showed lower ( 102-104 order) leakage currrent densities ( ~10-6 A/cm2 at 3 V) comparing with those of the sputtered BiFeO3 thin films. These experimental results indicate that the film growth under high oxygen pressure and precise film composition control in MOCVD process are indispensable for obtaining high quality BiFeO3 thin films with low leakage.