Ground penetrating radar (GPR) ground wave was used to monitor the surface soil-moisture content distributions at a natural Japanese Andiol (i.e., Kanto loam) site. The study site was maintained as bare during three month monitoring period. The results obtained from ground wave analysis showed non-uniformity in moisture content distribution. However the zones of higher moisture content were found at similar locations among different times, with or without precipitation events between observation times. This indicates that surface soil moisture dynamics are more-or-less location (i.e., topography, soil physical properties) dependent. Our study highlighted the use of GPR ground wave as a skillful way to execute noninvasive moisture content mapping of Japanese Andisol.