According to the present invention, a method for recovering useful fish meat proteins from waste water generated during fish paste or fishmeal production is provided. The provided is a method for recovering water-soluble proteins from fish paste leaching waste water or stick water, comprising: adjusting the pH of fish paste leaching waste water or stick water to 4.5-5.5 to insolubilize water-soluble proteins; heating the insolubilized proteins to 30° C. to 90° C. to cause the proteins to flocculate so as to form flocs; subjecting the flocs to solid-liquid separation using a decanter centrifuge during heating; and recovering proteins in the form of solid content.