Although Geranium soboliferum which is a native threatened species has grown wildly in the Nobeyama Highland located in Minamimaki village in Nagano Prefecture, the distribution range has narrowed by large-scale development of farmland at the postwar period and other reasons. In this study area, Miyahara and Okubo (2010) suggested that the distribution of G. soboliferum populatios overlaped some alien plant species such as Barbarea unlgaris and Oenothera biennis as the result of survey scale at 50 m in 2009. And it seemed that these alien plant species competition with G. soboliferum populations from now on. So, the purpose of this study was to clear that the competitive relationship between native threatened species such as G. soboliferum and alien plant species by the more smoll scale survey in 2011. The distribution survey were carried out using the portable GPS receiver. The dominance and the population size were measured in each study mesh. As a result, about eighty percent of the appearance mesh of G. soboliferum overlapped B. unlgaris or O. biennis. Also the percentages of overlap with Erigeron annuus or Erigeron strigosus were higher than other. In this survey too, the duplication rate with G. soboliferum and alien plant species were very high.