This study examines the changes in chlorogenic acid (CGA), an antioxidant, and one of its decomposition substances, caffeic acid, at various roasting stages and extraction conditions. Based on the CGA content for each roasting stage, at 3℃ after the beginning of the 1st crack, the CGA decreased for washed beans and natural beans by more than 50% compared to that of green coffees. The CGA continued to decrease sharply by more than 75% at the end of the 1st crack for washed beans and at 5℃ after the end of the 1st crack for natural beans. At the peak of the 2nd crack, it had decreased by more than 90% for both beans. The Caffeic acid content gradually increased for both washed and natural beans, then rapidly increased from the beginning of the 2nd crack to the peak of the 2nd crack. However, its contents were very small in quantity. Additionally, the content of CGAs for differing extraction conditions were in the order of 3-CGA, Crypto-CGA, and Neo-CGA. Crypto-CGA content was about half that of 3-CGA and Neo-CGA content was approximately 100 ppm less than that of Crypto-CGA. This study was conducted in order to help make coffee that has the most antioxidant effect.