After manufacturing sad persons extract, the scheme for making full use of the byproduct " sad person extracts son " being recovered is begun to. The present invention is sad persons extract Immune-enhancing effect feed addictive contained with validity point, from the woundeds extract abrogated as former state as feed addictive, while can also enhance the reinforcing effect of animal immune, also same with general drug with existing animal. The Immune-enhancing effect feed addictive improved the standard can be provided.