As has been reported in the part I, the author obtained the hepatitis virus, and IZUMI fever virus in purified form by means of ultracentrifuge method proposed by HASHIMOTO, and studied comparatively on some serological properties of these purified viruses. The results obtained were following. 1) The antiserum obtained by inoculation of the purified IZUMI fever virus (YASHIRO'S strain) had high titer and showed the titer of 1:64 on the complement fixation test to the YASHIRO'S strain, but did not give the positive reaction to the purified hepatitis virus when it was used as antigen. Vis-a-vis, the antiserum obtained by inoculation of the purified hepatitis virus showed the titer of 1:64-1:128 to the hepatitis virus and negative reaction to the IZUMI fever virus. Hence, in the view of complement fixation test, the serological properties of the viruses were evidently different. 2) Conerning to the results of neutralization reaction and “Absätigungsversuch” after WILDFÜHR, it could be postulated by the pathological findings the occurence of effective neutralization reaction when the test conducted between a virus and the antiserum obtained by inoculation of the same virus; contrarily to this the neutralization reaction between a virus and the antiserum obtained by the inoculation of other virus did not occur. Since the reaction thus observed was not so evident as the complement fixation reaction described above, sometimes it was hardly possible to identify the definite reaction. However, this reaction was still informative, especially in referential use of the reaction to complement fixation test, because of the occurence of certain inhibition or mitigantion of pathological changes as the result of the neutalizing effect. 3) From the facts described above, it could be concluded that the evident difference of properties was noticeable in both viruses tested despite of the presence of some similarity on serological properties.