Soybean (Glycine max L. Merr.) cultivars Bragg, CNS, Hill Akisengoku were used, these Rj genotypes were non-Rj, Rj_2 Rj_3, Rj_4 and Rj_4, respectively. Bradyrhizobium japonicum Is-1 and B. japoncum Is-34 were used as inoculum, and an effective nodulation by B. japoncum Is-1 is controlled by Rj_2 gene and that by B. japonicum Is-34 is controlled by Rj_4. After 24 hour of inoculation, the deformation of root hair was observed by using an optical microscope. Deformation of the root hair of Hill was recognized by the inoculation of a compatible strain Is-1, an imcompatible strain Is-34 or even non-inoculation. But, the frequency of deformation was highest when Is-1 was inoculated as a compatible strain and the main deformation was spiral type. The deformation of the root hair of Akisengoku was confirmed by all inoculation treatment, too. But, when the compatible strain Is-1 was inoculated, the main deformation was not only spiral type but also spatula type. The deformation of root hair was observed mainly at the position close to root tip but not at the position close to the basal root. Though the contact between the root hairs recognized as the previous stage of spiral type was confirmed, the root hair deformation considered as the previous stage of spatula type wasn't confirmed after 12 hour of inoculation in all soybean cultivars.