Web page legibility is important because of the wide-spread use of the World Wide Web, and color combinations between the foreground and background are crucial to assuring sufficient legibility. In our previous studies, the visibilities of several web-safe color combinations were examined using a psychological method. In those studies, simple stimuli were used because of experimental restrictions. In this study, the legibility of sentences on Web sites was examined using an oculomotor-based psychophysilogical method, and the effect of achromatic color combinations, that is, the contrast, was examined in terms of the calculated reading time. The presentation stimuli were positive colorations, whose font color luminance was lower than the background color, and negative colorations, whose font color luminance was higher than the background color. The number of characters per line was arranged to be the same on each page, and four levels of achromatic contrast (the contrast between the background color and the font color), namely, 92.5%, 75.0%, 50.0%, and 25.0%, were examined. It was shown that the reading time increased when the contrast decreased. However, with negative coloration, there were great differences between individuals. Therefore, considering web accessibility, legibility is found to be improved when using a positive coloration. (c) 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(9): 27-33, 2010; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ec1.10243