As a reduction strategy for global warming by green-house gases underground storage or sequestration of CO2 into coal beds or seams has been studied by the Japanese government and some associated organizations. The principle of this study depends on the adsorption of CH4 or CO2 on the surface of coal molecules as well as the nearly twice the amount of adsorption of CO2 compared with CH4. One of the authors had experimentally clarified the adsorption abilities of the coals in each Japanese coalfield. Based on these adsorption-abilities, the amount of the coal-bed methane resources was calculated, and also the sequestration-potential of carbon dioxide was estimated for each coalfield. In this paper, the CO2 sequestration-potential obtained from each coalfield is compared with the potentials from the other coalfields in Japan. Among the Japanese coalfields, the Ishikari coalfield in Hokkaido is the biggest and shows 50% of Japanese CO2-sequestration-potential. And the other big coalfields are the solitary island area in the northwestern district of Kyushu and the Miike-Ariake Sea area. Their potential percentages are 14% and 13%, respectively. (c) 2005 Elsevier Ltd. All rights reserved.