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Basic densities of wood from 10 species (572 trees) of softwoods and 50 species (440 trees) of hardwoods were measured as parameters for estimating the amount of carbon removal by forests following the guidelines described in the Kyoto Protocol and Marrakesh Accord. The basic densities of individual trees were averaged for each species and 95% confi dence limits were calculated for quality control. Furthermore, variations in the mean basic densities within species were assessed by analysis of variation and the effects of stand ages or tree ages on the basic densities were also evaluated. The average and 95% confi dence limits of the basic densities in most species that were collected for a certain number of sample trees converged and most species showed low uncertainty up to 5 %. Some species, such as Larix kaempferi, Picea jezoensis and Picea glehnii, showed signifi cant differences among plots, while other species, such as Chamaecyparis obtusa and Abies sachalinensis did not. When the basic densities were averaged for regional groups, the regional mean did not show signifi cant difference. Thus, the differences found between plots might not have been caused by regional variation. Moreover, neither the tree age nor the stand age showed signifi cant correlation with the basic densities; the basic densities of younger stands (younger than 20 years old) did not differ from those of the older stands. These results suggest that using basic densities as a parameter for estimating carbon removal by forests does not require the preparation of values for districts or age classes.