The effect of roasting intensity and extraction time of coffee bean on the antioxidant activity of roasted ground coffee extract was investigated. Coffee was roasted at 185oC using a rotating fluidized bed roaster for 5.17 (medium roasting) and 6.00 (dark roasting) min, respectively. Both roasted coffees were extracted in 90oC hot water according to the increased extraction time. Until 20 min, an increase in extraction time significantly increased soluble solute, caffeine, brown color, and phenolic compound. The soluble solid and caffeine contents showed no significant difference among medium- and dark-roasted coffee extracts. The brown color intensity and free radical scavenging activity of dark-roasted coffee extract were higher than those of medium-roasted coffee. On the contrary, the total phenolic content of dark-roasted coffee extract was lower than that of medium-roasted coffee. The free radical scavenging activity of coffee extracts showed a positive correlation with brown color intensity, as well as total phenolic content.