To investigate (1) the concurrent validity of the Nursing Home Life-Space Diameter (NHLSD) and the Home-based Life-Space Assessment (Hb-LSA), (2) the correlated factors of life-space, and (3) the factors that affected the NHLSD score for the elderly in a geriatric health service facility, or Roken. This cross-sectional study included 32 participants in a Roken. Staff members, who had received essential guidance for assessment, examined the cognitive function, physical function, mood, communication ability, objective quality of life, vitality, and daily behavior of the participants. Correlation analysis between NHLSD and other measurements and multiple regression analysis with NHLSD as a dependent variable were conducted. NHLSD and Hb-LSA were significantly correlated (r=0.710, P<0.01). NHLSD was significantly correlated with more measurements than Hb-LSA was; i.e., NHLSD was significantly correlated with communication ability, independence of daily living (Barthel Index; BI), maximum knee extension strength, grip strength, function in daily living, and three QOL measurements: positive affects, ability to communicate, and spontaneity and activity. A stepwise multiple regression analysis indicated that the BI total score, the maximum knee extension strength, and spontaneity and activity (one of the QOL items) were significantly correlated with the NHLSD score. NHLSD can measure the mobility levels of elderly persons in Roken. In addition to physical conditions and dependence of ADLs, spontaneity (or low levels of apathy) may be an important factor for promoting physical activity in Roken.