A batch-rectification experiment to remove a minute amount of furfural from ethanol aqueous solution was carried out by use of an Oldershow-type column consisting of ten plates. At first, the experiment was carried out under total reflux conditions. Furfural was concentrated on the seventh plate from the top, and side-cut was carried out at this plate. The plate efficiencies of ethanol and furfulal were obtained from the total reflux condition data. A mathematical model was constructed and distillation curves of ethanol and furfural were calculated. It was shown that the calculated curves of ethanol and furfural agreed with the observed ones.