Amounts of CO₂ fixed by net primary production and released by soil respiration were determined on big-cone pine plantation. Net primary production, which was determined by allometric method, was converted into CO₂. CO₂ evolution in forest ecosystems are mainly through soil and root respiration. In order to separate root respiration from soil respiration, root-free sites were made in stand. Litter removal sites were prepared to estimate CO₂ evolution through litter layer. Respiration was measured at every two weeks intervals from April 2001 through April 2002, and soil temperature and soil moisture were measured at the same time. Net primary production of this big-cone pine plantation was 25.7 t·ha^-1·yr^-1. The amount of CO₂ fixed by this plantation was 42.5 t CO₂·ha^-1·yr^-1, The amount of CO₂ released by soil respiration was 5.0 t CO₂·ha^-1·yr^-1. The relative contribution of root respiration and litter layer respiration to total respiration was 46% and 32%, respectively. Net amount of fixed CO₂ was 37.5 t CO₂·ha^-1·yr^-1 in this big-cone pine plantation. From this result, this big-cone pine plantation play a carbon sink source from the atmosphere.