In this experiment the protective ability of the guinea-pig serum as well as sugar and glucose against hemagglutine substance of Japanese B encephalitis virus was reported. In case 0.85% physiological saline water with 5% of inactive guinea-pig serum has been added to antigen, its antigen ability was seen to be made double, and protected from heat under 37°C. That protcctive ability has risen to the top at 5%. When we have prepared some antigens using 0.85% physiololgical scaline water that was added certain inactive guineapig serum to the extent of 2.5%, antigens which has a good titer, and can stand both for the temperature as well as duration of time, besides, preservable, moreover would not lose its specificity may be obtained. Turnip sugar, glucose as well as fruit sugar give certain injurious effect on antigens ; then its action bears close relalion to, not only density, but temperature and lapse of time. Such function of sugars could only be inhibited by antigen protein, a fact that hints at the cue for the future study of antigenal struchlre.