Author did the experiments of tissue cultures infected with the agents (mitani strain) of Umayado Diseases, and got the results as follows: 1) Author did the tests of sensitivity to R. tsutsugamushi infection in the established culture-cells and knew they have the big spectrum of infection to the cells like FL cells, H(E)L(A) cells and liver cells (Chang). They showed the specific cytopathic effects (CPE) with multiplication of R. tautsugamushi also. 2) It was possible to get the positive results in the infection tests to mouse with the agents which passaged in FL cells, and it is possible to do the quantitative tests of R. tsutsugamushi by inspecting of CPE as an infection indicators. These specific CPE supported to know the process of infection and growth of R. tsutsugamushi. 3) Growth process of R. tsutsugamushi is very similar with the bacterial cell division system (binary fission) and is very slow in time and specific in morphology.