A simple continuous production process of biodiesel fuel, fatty acid esters from oils with high content of free fatty acid (FFA), was constructed using the heterogeneous ion-exchange resin catalysts. In the system, the expanded-bed reactor packed with the cation-exchange resin catalyst for esterification of the FFA and that with the anion-exchange resin catalyst for transesterification of the triglyceride were connected in series. When the mixed solution of the crude rice bran oil with a 14 wt % FFA and alcohol was supplied to the proposed system, the fatty acid esters with a high conversion of more than 98.6% could be continuously produced without any extra operation such as dewaxing/degumming of the raw oil, removal of the byproduct, and addition of alcohol.