In order to study biochemical and serological properties of supernatant (Sf) and particulated (Rf) fractions of Sal. enteritidis, the author prepared two fractions by ultracentrifugation of ground cell suspension of the growing cell of two organisms. The organisms used throughout this study were selected among several strains of Sal. enteritidis in the light of virulence to mouse and were MURASHIMA's strain, which showed the highest virulence and TAKATA's strain, showed the lowest virulence. The following results were obtained. 1) Nitrogen and carbehydrate contents were very low in Rf compaired to Sf, especially it was markedly low in the case of nitrogen. 2) Rf showed oxidative ability only to succinate and lactata among the substrate related to TCA cycle, but Sf could oxidize many substrates tested in various degree. However, Rf Sf and of TAKATA's strain could oxidize only succinate in high degree. 3) The specific enzyme activity of Rf was not affected by irradiation of ultraviolet ray, but was decreased to 1/3~1/4 by exposure to heat, 56℃ 30 min., or by action of formalin or mersonin. 4) Antigenic capacities differed only little between Rf and Sf in the light of aggulutinin production to rabbit serum. 5) Rf gave less intense cutaneous reaction and was less virulent than Sf in examinations using rabbit, for the cutaneous test, and mouse, for the virulence test.