This study examined how the number of words senior high school students read in the one year extensive reading program would affect their self-assessed reading speed and the results of the reading comprehension test at a trial examination. The participants were 36 senior high school students in the eleventh grade. It yielded the following three results: first, this extensive reading program helped the students increase their reading speed regardless of their reading comprehension levels. Second, the more they read, the stronger tendency they showed toward reading faster. Third, the ability to read faster seemed to have a strong formative influence on their reading comprehension level. Thus, the study suggests that in order to read without much difficulty, students need to gain the reading speed by reading more through extensive reading programs.