A lot of water soluble proteins and lipids are released from minced mackerel meat and lost into the washing waste during the leaching process of Kamaboko or surimi manufacture. The removed proteins and lipids are not only an edible things but also a big burden for treating the wastewater. In order to recover the proteins from the effluent and to use as food stuff, the "pH-shifting" treatment, a modified isoelectric point precipitation method, was tried. This method is based on a myogen-aggregation phenomenon, which occurs when a solution of sarcoplasmic proteins is acidified or alkalified beyond the critical pH zone of 2∼3 or 12∼13 respectively and then neutralized. The maximum amount of precipitation was obtained by shifting the pH of the wastewater from original pH to isoelectric point (pH 4) or alkali pH 12 and then changing to neutral pH. The precipitates were easily collected by filteration or centrifuging at 10,000rpm. The oils which were only floating in the washing wastewater are easily recovered by seperating with oil separator after pouring. The recovered proteins were slightly denaturated during this pH shifting precipitation process, while the composition of amino acids was good balance as a food.