The image qualities of LCD and OLED monitors set to their own default settings were compared using forced-choice experiment method. Both displays’ peak white luminance was around 1,000 cd/m2 and color gamut setting was fixed as DCI-P3 for LCD while OLED’s gamut was set as DCI-P3 or BT.2020. The twelve image quality evaluation keywords were collected through the focus group Interview and eleven HDR video clips were selected as test stimuli. During the experiment, the test video was shown on two displays placed side-by-side and thirteen naïve participants were asked to select the display having the better image quality. The experimental results showed that OLED has higher image quality than LCD does because of higher colorfulness in general. Black luminance level affected the image quality for the dark images but the images having large bright area, colorfulness affected the overall image quality. This result shows that not display technology but the color characteristics affects the image quality.