To understand the relationships between understory bamboos and soil properties, we compared microbial communites structure of rhizosphere soil of Sasa kurilensis with Sasa-removed soil in a Betula ermanii boreal forest by a high-throughput DNA sequencing method. Understory Sasa strongly affected soil properties, such as total carbon, total nitrogen, nitrate and C:N ratio. Among fungal communities, the relative abundance of phylum Ascomycota in libraries was 13.9% in the Sasa-intact plot, while it was only 0.54% in the Sasa-removed plot. Most abundance value of phylum Ascomycota was attributed to family Pezizaceae. As for bacterial communities, phyla Acidobacteria, Proteobacteria and Planctomycetes were significant differences between the Sasa-intact and Sasa-removed plots. We found that the Pezizaceae, known as mycorrhizal fungi, was related to the amount of total carbon in the Sasa-intact plot. The lower abundance of genus Cryptococus in the Sasa-intact plot than that in the Sasa-removed plot confirmed that the rhizosphere of Sasa had a drier soil environment. Furthermore, the species richness results suggested that bacterial phyla may have symbiotic species with ectomycorrhizas under the presence of Sasa. These results indicated that microbial communities in rhizosphere of Sasa under drier soil environments have function to change soil properties in B. ermanii boreal forest.