Coarse woody debris (CWD) is an important component to carbon cycling in forest ecosystems. It was generally noticed that the formation and decomposition of CWD are influenced by various environmental factors. Therefore, it could be prospected that recent global warming and climate change have an effect on mass dynamics of CWD. The objective of this study is to provide data on long-term CWD mass dynamics in three different natural forests, Korea. CWD was investigated in a naturally regenerated deciduous forest dominated by Q. mongolica , a mixed forest dominated by A. holophylla , and a pine forest dominated by P. densiflora at Mt. Jumbong, Korea. Total mass of CWD (t/ha) for the Q. mongolica forest decreased from 24.5 in Nov. 2003 to 17.5 in Nov. 2008. In addition, total CWD mass (t/ha) for the P. densiflora and A. holophylla forests decreased from 7.1 and 28.9 in May 2006 to 6.4 and 18.6 in Nov. 2008, respectively. Annual input and decomposition of CWD (t/ha/yr) was 0.3 and 1.3 for the Q. mongolica forest, 0.3 and 2.0 for the A. holophylla forest, and <0.1 and 0.1 for the P. densiflora forest, respectively. The majority of the CWD mass in the Q. mongolica forest was classified into decay class III (57.2%), followed by classes II (27.5%), IV (12.2%), and I (3.2%).