Atmospheric aerosols such as Asian dust particles and PM2.5 are transported to ocean area, such as East/Japan sea and Pacific Ocean. The aerosol deposition provide nutrients, trace metals, and organic compounds over marine environments that enhance ocean productivity and carbon sequestration, and indirectly influence the atmospheric carbon dioxide concentrations and climate change. However, microbial dynamics in the seawater which aerosols deposited are limited to be analyzed using chemical analysis of field survey and model analyses, and there are a few of direct survey the effects of aerosol deposition on microorganisms. In this study, the snow samples including aerosols were collected from the snow cover of Mt. Tateyama, a shipboard experiment using the seawater spiked with snow samples was performed for elucidating the influence of aerosol additions on the growth and community structures of marine microorganisms. The seawater spiked with snow solution was incubated on a shipboard at the oligotrophic (May in 2012 and 2013) and eutrophic (November in 2012 and 2013) marine area in Pacific Ocean. The chlorophyll concentrations at fractions of several sizes and pigments types of four phytoplankton categories in the seawater samples were measured for understanding the dynamics of phytoplankton, which are influenced by aerosol depositions. Bacterial community structures were also analyzed using pyrosequencing and clone library techniques targeting 16S rDNA gene sequences. In the case of oligotrophic condition, the aerosol depositions would increase the primary products of phytoplankton significantly and specific bacterial communities belonging to Cyanobacteria and Alpha-proteobacteria. Presumably, the aerosol deposition can potentially alter microalgal amounts and bacterial communities structures in marine environments.