The more proficient learners are at a foreign language, the faster they can process that foreign language; hence, processing speed is one of most important indices of foreign language proficiency. Yet there are few studies which examine the relationship between proficiency levels and processing speeds. In the present study, I looked at how the English proficiency test scores of 35 Japanese learners related to the speed at which the learners processed written English sentences. The results showed a statistically robust correlation between listening test scores and the processing speed of sentences which subjects read (p < 0.05), but not between reading test scores and general processing speed (p = 0.5). These results indicate that the reading speed of sentences in a foreign language is strongly related to listening proficiency, which proceeds to suggests that reading speed in a foreign language can be used as one index of listening proficiency.