The amount of food waste has been increasing every year. Food waste takes relativity high portion of domestic waste and we have much difficulty in treating it. Most of food wastes are landfilled or incinerated after drying for the reduction of water content. The operation cost of the landfill and the incineration are very high. To solve the landfill and the incineration problems in recent years, the recycling of food waste was used by the methods of turning food waste into animal food and fertilizer. Food wastes are compatible to be used as feedstock of the fermentation because they contain valuable nutrients. Among these situations, organic acids, which are effectively used in a variety of industrial processes, can be considered to be a high cost value-added products. The purpose of this study is to evaluate the possibility of organic acid concentration using a MF/RO system. A MF/RO system was believed to be an effective one for the concentration of organic acid from food waste. Water quality of fermentation broth, MF permeate and RO retentate in terms of conductivity, pH, electric conductivity, TS (Total solids), TDS (Total dissolved solids), CODcr concentration, chloride ion concentration was examined as analytic items. pH of fermentation broth was higher than that of MF permeate and RO retentate due to the concentration of organic acid. pH of RO retentate was about 4. Conductivity, TDS, CODcr and chloride ion of RO retentate were about 1.3, 1.3, 2.9, 4.5 times higher than that of fermentation broth, respectively and TS reduced about 0.8 times. This may be ascribed to separate effectively the solid-liquid separation by MF and RO rejection. Consequently, a MF/RO system is believed to be applicable for the concentration of organic acid from fermentation broth of food waste.