Abstract: KS-substance was obtained as raw material from the cultured mycelium of Daedalea dickinsii KSDD 6 (FERM-P No. 3993), Lentinus edodes KSLE 7 (FERM-P No. 3994) or Lentinus edodes KSLE 28 (FERM-P No. 4196), and by refining this substance a novel substance KS-2-A was obtained. This substance KS-2-A and also the KS-substance as the raw material both enhance the host defense function of the living body.