Treatment of waste water discharged from sweet potato shochu distillery with yeasts was studied. The solid-liquid separation of the distillery waste water was carried out effectively by adding Trichosporon M 111 cells which showed the aggregation-accelating ability of insoluble solid in the waste water. The filtrate was treated with the waste-treating yeast strain, Hansenula anomala J-224. Consequently, 65% of BOD was removed from filtrate. In addition, to remove the solids, the filtrate was subjected to the treatment with the yeast-lytic bacteria, Rarobacter faecitabidus, which have lytic-ability against the strain J-224. By this treatment, the solid concetration was lowered to 0.7% from 1.4%. The resulting filtrate, if diluted to ca. 3 times with cooling water discharged from the distiller, could be subjected to the active-sludge treatment.