We have compared usability of paper/PC/e-Paper (electrophoretic display) proceeding books assuming they were used by audiences during a conference.Subjects were requested to point out the difference between the figures in slides and proceeding when they were assumed to be audiences for a short presentation of 5 minutes. Correct answer rates were evaluated when they were using the three different medium respectively. The e-Paper proceeding showed better preference, in subjective evaluation, than PC proceeding. Full page showing by e-Paper may be preferred than partial page showing by PC. The e-Paper proceeding has shown, however, lower answer rate than the other two mediums. The longest time, on e-Paper, required for paging was assumed as the cause of the lowest correct answer rate shown for the e-Paper proceeding book.