The purpose of this paper is to investigate the readability of Nearly White background color in display environment. To perform the experiment, warmup experiment was carried out to for cognitive of whiteness using a Tablet PC. The experiment environment was by a indoor window seat under a mixture of fluorescent light and sunlight. The result of previous test was that the most whiteness perception was a color white a medium wavelength and followed by the short wavelength. The main experiment was to find readability, color combination and visual strains using 4 nearly whites background colors (Reddish, Greenish, Blueish, Yellowish) and one white background color, also text color is limited on black. As a result, readability and color combination had the highest score against a Greenish white background. Visual strain is also the lowest against a Greenish background. On the contrary, readability and color combination preference has the lowest score against the Reddish background. Visual strain is also the highest against a Reddish background. We propose the background color, which improves readability and reduces visual strain in visual display terminals environment through the research results.