It has been recognized that the protein contained in waste water from fish paste-manufacturing factories could be recovered effectively by electrocoagulation. In this process, the waste water is passed in a continuous flow through the electocoagulating vessel from the bottom upwards. The conditions required to obtain the most favorable results, i.e., 95.8% respectively of the crude protein (CP) and 61.1 and 62.3% reduction of COD and SS, respectively, were as follows. Electrocoagulating vessel: a cylinder having bottom area (cm2) and height (cm) dimensions in ratio of 1:1. Electrodes: an iron plate charged negatively at the top of the vessel, and a carbon plate charged positively at the bottom. Flow rate of waste water: a volume of waste water flowing through the electro- coagulating vessel per hour approximately equal to the volume of the coagu- lating vessel. Voltage and electric current: 380 V and 440mA for a vessel of four liters. The current concentration was rather high on the basis of laboratory experiments, but might be reduced by the improvement of equipment design.