Biological diversity has inherent value and becomes the basis of various ecosystem services that humans assume support their survival. On the other hand, biological diversity is being lost throughout the world, and the conservation of biological diversity is an extreme problem. National Strategy for the Conservation and Sustainable Use of Biological Diversity 2008 Version (Ministry of the Environment, November, 2008) raises “The conservation in an important area and the formation of the ecological network” as one of seven main themes for conservation of biological diversity and sustainable use. As a part of the construction of an ecosystem network, a policy to set “a green corridor” in the national forests was enforced in 2000 by the Forestry Agency. In this study, “The green corridor of Shikoku Mountainous District” (Tokushima/Ehime/Kochi) was selected from the green corridors set in 22 places in Japan for investigation. Local populations of the Asiatic black bear inhabiting the Shikoku mountainous district are listed in the Red Data Book of Ministry of the Environment for fear of extinction and the fear of extinction is on the rise. Distribution of the Asiatic black bear appears to be limited to the Mt. Tsurugi-san area of “The green corridor of Shikoku Mountainous District” and the surrounding area and “The green corridor” is highly associated with the conservation of this population. The current corridor may not be able to network a suitable habitat for securing a minimum viable population size (MVP) of the Asiatic black bear as calculated by the individual base model. In addition, when it thought about building of the ecological network, there were the places to overlap with the natural park and so on in the corridor. It is necessary to set a broad corridor that includes private and communal forests in the area by cooperating with other measures of the natural park or natural conservation area, the sanctuary. However, most of the private and communal forests in this area are economic forests and forestry is a major local industry. An estimate of the expenses and the burdens to push forward this policy must be considered. JEL Classification: Q2, Q5