This paper investigates the effect of subject's age on web-safe color visibility on a white background. An evaluation of website accessibility is necessary because of the rapid dissemination of information on the World Wide Web. One important factor to be considered when developing accessible websites is the foreground color and the background color combination. In this study, the visibility of 21 chromatic web-safe colors on a white background was examined using a psychological methodology, i.e. a paired comparison. The participants in the experiment were 12 young adults, 17 middle-aged adults and 11 elderly adults. The young adults conducted three tests involving 420 paired-comparison trials while the other groups' participants conducted the test in consideration of the physical burden. It was found that the chromaticity of the foreground color influenced the assessment of the page's visibility by the young adult group more strongly than that by the other groups. It was also found that the contrast between the foreground and background colors affected the assessment of the page's visibility by the middle-aged and elderly groups more strongly than that by the young adult group. This indicated that the ageing effect in the visibility increases the effect of the contrast and decreases the effect of the chromaticity.