The response of respiration rates of root, A_0 layer and mineral soil to varying environmental factors was studied in Populus maximowiczii stand (25-year-old) during the growing season of 1997. Soil temperature showed a pronounced seasonal course, in contrast to soil moisture. The mineral soil respiration was high in August. and root and A_0 layer respiration, were high in July. An exponential equation best described the relationships between soil temperature and mineral soil respiration. and total soil respiration (r=0.95 and 0.92, p＜0.001), respectively. In P maximowiczii stand, soil respiration rates were reduced by about 19% after removal of the A_0 layer, and by about 30% after removal of living root. Therefore, mineral soil respiration seemed to contribute gretly to the total soil respiration (50%).