For the purpose of investigating the effect of soil microflora on the growth of Bupleurum falcatum (B. falcatum), colony forming units (CFU) of bacteria, gram-negative bacteria, fluorescent Pseudomonas species, actinomycetes, facultative anaerobes, fungi and yeast in the non-rhizosphere soil, rhizosphere soil and rhizoplane of B. falcatum cultivated under 3 kinds of soils with and without ventilation were assayed. Although the conditions of cultivation were different among each experimental field, CFU of fluorescent Pseudomonas species and actinomycetes had a highly positive correlation with the growth of B. falcatum. A negative correlation between CFU of fungi and the growth of B. falcatum was also observed. These results suggested that populations of these microorganisms are closely related to the growth of B. falcatum.