This study conducted a subjective evaluation of brightness perception and visual discomfort according to dimming speeds and CCTs(Correlated Color Temperatures). Dimming speeds of two different CCT lights(2,700K, 6400K) were set to 1.7%/s, 3.3%/s, 5.0%/s, 6.7%/s, and 10.0%/s respectively. Subjects checked the time when they perceived the change of the brightness and visual discomfort. As a result, when dimming speeds were 1.7%/s, 3.3%/s, 5.0%/s, 6.7%/s, more than half of subjects responded the change of the brightness in 55.0~45.0% dimming ratios, and felt the visual discomfort in 35~25% dimming ratios. When the brightness was changed, dimming level responded to the brightness perception of hight CCT(6,400K) was higher about 8.0% then dimming level responded to the brightness perception of low CCT(2,700K). Dimming level responded to the visual discomfort of low CCT(2,700K) was higher about 5.0% then dimming level responded to the visual discomfort of hight CCT(6,400K).