The relationship between environmental factors and the occurrence of the Smith's redbacked vole, Eothenomys smithii, was analyzed first by principle component analysis (PCA) to select factors and suitability of fit between capturing results of the voles, and subsequently by multiple regression analysis (MRA) to identify significant environmental factors affecting the occurrence of the vole. Six research sites were established along six valleys showing rocky terrain in the Tenshi Mountains at the foot of Mt. Fuji, Shizuoka Prefecture, Honshu, Japan, where the closely related species, E. andersoni, is absent. Ten environmental factors were examined for the occurrence of the vole in three quadrats at each site. In addition, thirty traps were set at 5-m intervals along the valley (150 m long) for one night at each site, and this trapping was performed four times in one year. As a result of MRA, higher coverage of bryophytes (factor 9) was significantly chosen among the four factors primarily selected by PCA. It is concluded that E. smithii prefers a dense covering of bryophytes in the rocky terrains of small valleys with forests, suggesting conditions of higher moisture and darkness appropriate for bryophyte growth.