Concentrations of organically-bound ¹⁴C in the tree-ring cellulose of a Japanese Cedar (Cryptomeria japonica) grown in a rural region of Kanazawa, Ishikawa prefecture, Japan (36.5°N, 136.7°E), were measured for the ring-years from 1989 to 1998 to study relationship between ¹⁴C concentrations in tree-ring cellulose and atmospheric CO₂ in a narrow region. An interesting result in comparing our data of tree-ring cellulose with those of atmospheric CO₂ is that the ¹⁴C concentration in tree-ring cellulose was close to the corresponding average from mid-June to early September of ¹⁴C concentrations in atmospheric CO₂. Furthermore, the ¹⁴C concentrations in tree-ring cellulose were found to be merely influenced by the drastic decrease of ¹⁴C concentrations in atmospheric CO₂ in winter, which might be caused by air pollution from the Asian continent and additional local fossil fuel contribution. These results suggest that the ¹⁴C concentration in tree-ring cellulose for a given growing year reflects the ¹⁴C concentrations of atmospheric CO₂ during the warm summer months.