Groundwater is one of the most important sources for agricultural purposes. Recently, a deterioration of the groundwater resources quality has been observed due to increasing anthropic activities, which also lead to widespread emerging contaminants. Among them, the source of Microplastics (MPs) in groundwater is relatively less explored, although MPs are becoming an important issue due to their persistency in the environment. For example, "coated fertilizer", which is one of the chemical fertilizers, has been recently used in agricultural activity. Some papers have reported the presence of this coated fertilizer as well as the debris of plastics in groundwater.[1][2] In this research, we characterized and quantified MPs in ground water from Kumamoto City, Kumamoto Japan, which is 100% groundwater as a source of tap water and has been used for agricultural supplies, Groundwater samples were collected from springs and/or shallow wells which are located at agricultural areas and urban areas in Kumamoto City in 2022. Ground water from most of the sites had been analyzed for inorganic chemical composition. Individual water samples were filtered, dried and examined with a microscope. After that, FT-IR is used as the filter paper to demonstrate whether microplastics are detected. Some groundwater samples collected during this investigation contained microplastics, with a median concentration of several particles/L. Our work shows that topography and associated aquifers allow for the movement of microplastic fibers into groundwater flow systems.